🧮 Mathematics Basic — Class X
Simpler questions, same chapters. Focus on concepts and application.
🏅 Badges
📖 Key Concepts
🔑 Master Formulae
✏️ Worked — HCF by Euclid (Board 2023, 2M)
Q: Find HCF(252, 105).
✏️ Worked — Decimal Type (Board 2022, 1M)
Q: Is 17/8 terminating or non-terminating?
📝 Chapter MCQs
Options: (A) 1 (B) 2 (C) 3 (D) 5
Ans: (A) 1 — all three are co-prime with each other.
(A) √9 (B) √25 (C) √7 (D) √16
Ans: (C) √7 — 7 is prime, so √7 is irrational.
(A) Terminating (B) Non-terminating recurring (C) Non-recurring (D) None
Ans: (A) — 20 = 2² × 5, so it terminates. 7/20 = 0.35.
(A) 100 (B) 150 (C) 216 (D) 300
Ans: (B) 150 — LCM = 1800 ÷ 12 = 150.
(A) Rational (B) Irrational (C) Integer (D) Fraction
Ans: (A) Rational — √2 × √8 = √16 = 4, a rational number.
🔁 Assertion–Reason
Reason (R): Square root of any positive integer is irrational.
Options: (A) Both A and R are true, R is the correct explanation (B) Both true, R is NOT correct explanation (C) A true, R false (D) A false, R true
Ans: (C) — A is true (√5 is irrational). R is false — √4 = 2 is rational.
Reason (R): A fraction p/q terminates if q = 2m × 5n.
Ans: (A) — 6/15 = 2/5; denominator 5 = 5¹ ✓. R correctly explains A.
📦 Case-Based Question
Passage: A school timetable committee is scheduling periods for Music (every 36 minutes) and Sports (every 54 minutes). Both start at 8:00 AM. The committee also wants to know if the total minutes in the school day (360 min) can be written as a product of primes.
✍️ Short Answer (2–3 Marks)
Ans: Assume √3 = p/q (lowest terms). Then 3 = p²/q², so p² = 3q². Thus 3 | p², so 3 | p. Let p = 3m. Then 9m² = 3q², so q² = 3m², meaning 3 | q. But then 3 is a common factor of p and q, contradicting our assumption. ∴ √3 is irrational. ✓
Ans: 510 = 2 × 3 × 5 × 17; 92 = 2² × 23. HCF = 2. LCM = 2² × 3 × 5 × 17 × 23 = 23460.
📘 Long Answer (5 Marks)
Ans: (i) LCM(6,12,18) = 36 minutes. (ii) 3 hours = 180 min; 180 ÷ 36 = 5 times (not counting 8:00 AM start). (iii) 36 is rational — it equals 36/1, which is p/q form with q ≠ 0.
📖 Key Concepts
🔑 Quadratic Zeroes Formulae
✏️ Worked — Find zeroes (Board 2023, 2M)
Q: Find zeroes of p(x) = x² − 5x + 6 and verify.
📝 Chapter MCQs
(A) −1, 4 (B) 1, −4 (C) −1, −4 (D) 1, 4
Ans: (A) — (x−4)(x+1)=0.
(A) x²+3x−10 (B) x²−3x+10 (C) x²−3x−10 (D) x²+3x+10
Ans: (C) x²−(sum)x+(product) = x²−3x−10.
(A) 1 (B) 2 (C) 3 (D) 4
Ans: (C) 3
🔁 Assertion–Reason
R: The discriminant b²−4ac = 0−4 = −4 < 0.
Ans: (A) Both true, R correctly explains A.
📦 Case-Based Question
Passage: A garden path is rectangular. Its area is represented by p(x) = x² + 5x + 6 square metres, where x is a positive integer.
✍️ Short Answer
Ans: α+β = −5/2; αβ = −12/2 = −6. 1/α + 1/β = (α+β)/(αβ) = (−5/2)/(−6) = 5/12.
📖 Key Concepts
🔑 Consistency Conditions
✏️ Worked — Elimination (Board 2023, 3M)
Q: Solve: 2x + 3y = 11 and 2x − 4y = −24.
📝 Chapter MCQs
(A) unique solution (B) no solution (C) infinitely many (D) none
Ans: (C) — ratios 1/2 = 1/2 = 5/10, same line.
(A) intersecting (B) coincident (C) parallel (D) perpendicular
Ans: (C) Parallel — 3/9 = 1/3 = −1/−3, but 2/12 ≠ 1/3.
🔁 Assertion–Reason
R: The two equations represent the same line.
Ans: (A) Both correct, R explains A.
📦 Case-Based
Passage: Two friends Riya and Priya together have 45 marbles. Riya has 15 more than Priya. Let Riya = x, Priya = y.
✍️ Short & Long Answer
Ans: x = 1 + y → 3(1+y) + 2y = 10 → 5y = 7 → y = 7/5; x = 1 + 7/5 = 12/5.
Ans: Let boat speed = b, stream = s. Up-speed = b−s, down-speed = b+s. Equations: 32/(b−s) + 36/(b+s) = 7 and 40/(b−s) + 48/(b+s) = 9. Let u = 1/(b−s), v = 1/(b+s). Solve: u = 1/8, v = 1/12. So b−s = 8, b+s = 12. Therefore b = 10 km/h, s = 2 km/h.
📖 Key Concepts
🔑 Key Formulae
✏️ Worked — Discriminant (Board 2023, 3M)
Q: Find the nature of roots: 2x² − 4x + 3 = 0.
📝 MCQs + A-R
(A) k=1 (B) k=2 (C) k=−1 (D) k=0
Ans: (A) k=1 — D=4−4k=0 → k=1.
(A) 2, 5 (B) −2, −5 (C) 2, −5 (D) −2, 5
Ans: (A) 2, 5
R: D = 0 − 4(1)(1) = −4 < 0.
Ans: (A) Both correct, R correctly explains.
📦 Case-Based + SA + LA
Passage: A rectangular field has length 4 more than breadth. Area = 96 m². Let breadth = x.
Ans: D = k² − 48 = 0 → k = ±4√3.
Ans: Speed = x; 360/x − 360/(x+5) = 1 → 360(x+5) − 360x = x(x+5) → 1800 = x²+5x → x²+5x−1800=0 → (x+45)(x−40)=0 → x = 40 km/h.
📖 Key Concepts
🔑 AP Formulae
✏️ Worked — Sum problem (Board 2022, 4M)
Q: Find number of terms in AP 3, 7, 11... whose sum = 406.
📝 MCQs + A-R
(A) 31 (B) 35 (C) 27 (D) 39
Ans: (A) 31 — a=−5, d=4; a₁₀ = −5+36 = 31.
(A) 45 (B) 55 (C) 50 (D) 60
Ans: (B) 55 — S₁₀ = 10/2 × 11 = 55.
R: Common difference between consecutive terms is not constant (2, 4, 8...).
Ans: (A) Both correct, R explains A.
📦 Case + SA + LA
Passage: A student saves ₹1 on day 1, ₹2 on day 2, ₹3 on day 3, continuing for 30 days (an AP).
Ans: a₇ = a+6d = 13; a₁₁ = a+10d = 21. Subtract: 4d = 8 → d = 2. a = 13−12 = 1. AP: 1, 3, 5, 7...
📖 Key Concepts
🔑 Key Results
✏️ Worked — BPT (Board 2023, 3M)
Q: In △ABC, DE ∥ BC. AD = 3, DB = 5, AE = x, EC = 10. Find x.
📝 MCQs + A-R
(A) 3/5 (B) 6/10 (C) 9/25 (D) 27/125
Ans: (C) 9/25
(A) 8.94m (B) √80m (C) 4√5m (D) Both B and C
Ans: (D) — √(144−64) = √80 = 4√5.
R: All corresponding angles are equal (90°) and corresponding sides are proportional.
Ans: (A)
📦 Case + SA + LA
Passage: Two poles of height 6m and 11m stand on level ground. Wires connect their tops to the base of the other pole. Point of intersection of wires is at height h from ground.
Ans (outline): Standard proof using similar triangles (construct altitude to hypotenuse). Converse: if c²=a²+b², it's right-angled. Check: 8²+15²=64+225=289=17². ✓ Right-angled at the angle between 8 and 15.
📖 Key Concepts
🔑 Key Formulae
✏️ Worked — Distance (Board 2022, 2M)
Q: Show that A(3,−2), B(1,0), C(−1,2) are collinear.
📝 MCQs + A-R + Case
(A) (1,3) (B) (2,6) (C) (1,2) (D) (−1,3)
Ans: (A) (1,3)
(A) 25 (B) 5 (C) 7 (D) 12
Ans: (B) 5 — √(9+16)=5.
R: Area of triangle formed = 0.
Ans: (A) Both true, R correctly explains A.
Passage: A city map has three bus stops at A(1,2), B(7,5), C(4,−1). A new stop D divides AB in ratio 2:1.
Ans: Area = ½|2(0+4)+(−1)(−4−3)+2(3−0)| = ½|8+7+6| = ½×21 = 10.5 sq units.
📖 Key Concepts
🔑 Standard Values Table
✏️ Worked — Identity Proof (Board 2023, 3M)
Q: Prove: (sin A − 2sin³A)/(2cos³A − cos A) = tan A.
📝 MCQs + A-R
(A) 0 (B) 1 (C) √3/2 (D) ½
Ans: (B) 1 — This is sin(60°+30°) = sin 90° = 1.
(A) 0 (B) 1 (C) 2 (D) √2
Ans: (C) 2 — tan 45°=1; cot 45°=1. Sum=2.
R: Complementary angle identities relate trig ratios of complementary angles.
Ans: (A) Both correct, R explains A.
📦 Case + SA + LA
Passage: A student notices that a right triangle has perpendicular = 5 and hypotenuse = 13. All six trig ratios are asked.
Ans: (1/2)² + 2(1/√2)² + (√3)² = 1/4 + 1 + 3 = 4¼ = 17/4.
Ans: RHS = sin²A/(1−cosA) = (1−cos²A)/(1−cosA) = (1−cosA)(1+cosA)/(1−cosA) = 1+cosA = 1 + 1/secA = (secA+1)/secA = LHS ✓
📖 Key Concepts
🔑 Quick Reminders
✏️ Worked — Tower Height (Board 2023, 3M)
Q: A tower casts a shadow 40m long. Angle of elevation of sun is 30°. Find height of tower.
📝 MCQs + A-R
(A) 30° (B) 45° (C) 60° (D) 90°
Ans: (B) 45° — tan θ = 6/6 = 1 → θ = 45°.
R: They are alternate interior angles formed by a transversal with parallel lines.
Ans: (A)
📦 Case + SA + LA
Passage: From the top of a 75m building, two cars are seen on opposite sides. Angles of depression are 60° and 45°.
Ans: d₁ = 100/tan30° = 100√3; d₂ = 100/tan60° = 100/√3 = 100√3/3. Total = 100√3 + 100√3/3 = 400√3/3 ≈ 231 m.
📖 Key Concepts
🔑 Key Theorems
✏️ Worked — Tangent Length (Board 2022, 2M)
Q: PA is tangent from P to circle (centre O, radius 5cm). OP = 13cm. Find PA.
📝 MCQs + A-R + Case
(A) 4 (B) 8 (C) 10 (D) 16
Ans: (B) 8 — √(100−36) = √64 = 8.
R: The tangents are equal in length.
Ans: (B) Both true, but R does not directly explain A (the reason is OA=OB and OA⊥PA, OB⊥PB and OP common → congruent triangles → equal angles).
Passage: A circle has centre O and radius 7cm. P is 25cm from centre. Two tangents PA and PB are drawn.
📖 Key Concepts
🔑 Key Formulae (use π = 22/7 unless told otherwise)
✏️ Worked — Sector (Board 2023, 3M)
Q: Find area of sector with r = 14cm and θ = 45°.
📝 MCQs + A-R + Case
(A) 38.5 cm² (B) 77 cm² (C) 154 cm² (D) 22 cm²
Ans: (A) 38.5 cm² — ¼ × 22/7 × 49 = 38.5.
R: Minor segment corresponds to minor arc (angle < 180°).
Ans: (A)
Passage: A brooch has a silver circle of diameter 28mm. Six sector-shaped petals each with angle 60° are cut out of it.
Ans: Corner angle = 90°. Area for 5m rope = (90/360)×π×25 = 25π/4 = 19.625 m². For 7m rope: 49π/4 = 38.5 m².
📖 Key Concepts
🔑 All Formulae in One Place
✏️ Worked — Conversion (Board 2023, 3M)
Q: A cone (r=5cm, h=12cm) is melted and recast as a sphere. Find radius of sphere.
📝 MCQs + A-R + Case
(A) 66 cm³ (B) 198 cm³ (C) 22 cm³ (D) 44 cm³
Ans: (A) 66 cm³ — ⅓×22/7×9×7=66.
(A) 462 cm² (B) 308 cm² (C) 154 cm² (D) 616 cm²
Ans: (A) 462 cm² — 3πr² = 3×22/7×49 = 462.
R: Mass is conserved; since density is same, volume is conserved.
Ans: (A)
Passage: A toy is in the shape of a cone surmounted on a hemisphere, both of radius 3.5cm. Height of cone = 4cm.
📖 Key Concepts
🔑 Key Formulae
✏️ Worked — Mode (Board 2023, 3M)
Q: Find mode for: Classes 10-20, 20-30, 30-40, 40-50 with frequencies 6, 11, 14, 5.
📝 MCQs + A-R + Case
(A) 3 (B) 3.5 (C) 4 (D) 5
Ans: (B) 3.5 — Sorted: 1,1,2,3,4,5,6,9. n=8; median=(3+4)/2=3.5.
R: At the median, the cumulative frequency is n/2.
Ans: (A) Both true, R correctly explains A.
Passage: Monthly wages (₹) of 50 workers: 6000-7000: 5 workers; 7000-8000: 10; 8000-9000: 20; 9000-10000: 10; 10000-11000: 5.
Ans: n=100. Midpoints: 5,15,25,35,45. Σfx=8×5+16×15+36×25+34×35+6×45=40+240+900+1190+270=2640. Mean=26.4. Cumulative: 8,24,60,94,100. n/2=50; median class=20-30. Median=20+[(50-24)/36]×10=20+7.22=27.22.
📖 Key Concepts
🔑 Common Probability Facts
✏️ Worked — Card Problem (Board 2023, 2M)
Q: From a deck of 52 cards, find P(king) and P(not a face card).
📝 MCQs + A-R + Case + SA + LA
(A) 1/6 (B) 7/6 (C) 0 (D) 1
Ans: (C) 0 — Impossible event; 7 is not on a standard die.
(A) ¼ (B) ½ (C) ¾ (D) 1
Ans: (B) ½ — Favourable: {HT, TH} = 2 out of 4.
R: 2 is the only even prime; P = 1/6.
Ans: (A) Both correct, R explains A.
Passage: A bag has 4 red, 3 blue, and 5 green balls. One ball is drawn at random.
Ans: P = 12/60 = 1/5.
Ans: Total = 30. (i) Primes: 2,3,5,7,11,13,17,19,23,29 = 10 → P = 10/30 = 1/3. (ii) Div by 5: 5,10,15,20,25,30 = 6 → P = 6/30 = 1/5. (iii) Perfect sq: 1,4,9,16,25 = 5 → P = 5/30 = 1/6. (iv) >25: 26,27,28,29,30 = 5 → P = 5/30 = 1/6.
✏️ Worked Examples
Problem 1 — AP and Sum (Board 2023, 4M)
Q: How many terms of AP: 3, 7, 11, 15... are needed so that sum = 406?
📝 Practice Papers
Full-length 80-mark board-pattern papers · Mathematics Basic X
MATHEMATICS BASIC X — PRACTICE PAPER 1
Time: 3 Hours | Max Marks: 80 | CBSE 2024-25
MATHEMATICS BASIC X — PRACTICE PAPER 2
Different chapter focus
MATHEMATICS BASIC X — PRACTICE PAPER 3 (Challenge)
Slightly harder — for extra practice
Answer: 96 = 2⁵ × 3; 404 = 2² × 101; HCF = 2² = 4.
Also asked: Prove √3 irrational (proof by contradiction), LCM × HCF = product of two numbers (always verify).
Answer: (x + 2)(x + 3) = 0 → x = −2 or x = −3.
Also asked: Complete the square method, quadratic formula, nature of roots (b²−4ac).
Answer: By BPT: AD/DB = AE/EC → 3/4 = 2.4/EC → EC = 3.2 cm.
Also asked: Pythagoras theorem proof, similar triangle area ratio.
Answer: d = √[(3−(−2))² + (4−(−8))²] = √[25 + 144] = √169 = 13 units.
Also: Midpoint, section formula, area of triangle using coordinates.
Strategy: Expand LHS, use sin²+cos²=1, 1+tan²=sec², 1+cot²=cosec². Always expand the more complex side.
Also asked: Values of sin/cos/tan 30°, 45°, 60° applied in equations.
3-mark Q: Find mean using assumed mean method from frequency table. Set up: d = x − A, Σfd, apply formula x̄ = A + Σfd/Σf.
5-mark Q: Median from cumulative frequency ogive — plot and find n/2 point.
Answer: TSA = πrl + πr² = π(6)(10) + π(36) = 60π + 36π = 96π = 301.44 cm².
Also asked: Cylinder + hemisphere combination, volume of frustum, conversion questions.
Answer: P = 4/52 = 1/13.
3-mark Q (2023): Two dice rolled — find P(sum = 7). Sample space = 36; favourable = (1,6),(2,5),(3,4),(4,3),(5,2),(6,1) = 6; P = 6/36 = 1/6.
Fix: Write the three Pythagorean identities at the top of every trig proof as a reference before starting. They are: sin²+cos²=1, 1+tan²=sec², 1+cot²=cosec².
Fix: Write the formula explicitly: x = [−(−5) ± √1] / 2 → [5 ± 1]/2 = 3 or 2. Box the formula first, substitute second.
Fix: Class mark = (lower + upper) / 2 always. For 10–20 → (10+20)/2 = 15. This error affects the entire mean calculation.
Fix: Always simplify probability fractions. Check HCF of numerator and denominator before writing final answer.
Fix: BPT states: if DE ∥ BC then AD/DB = AE/EC (parts, not whole). Draw the diagram and label before applying formula.
Fix: Equal tangents from external point is used in 90% of CBSE circle tangent problems. Draw the figure — PT² = PO² − r².
5-mark question: 1 mark formula + 2 marks working + 1 mark correct steps + 1 mark final answer.
If final answer is wrong but all steps are correct → 4/5 marks. Never leave a question blank.
These are the easiest marks in the paper — don't skip them.
Must know: P(event) = favourable outcomes / total outcomes. Cards: 52 total, 4 suits of 13 each. Dice: 36 outcomes for two dice. These are calculation-free if sample space is memorised.
Formulas: Mean = A + Σfd/Σf; Mode = l + [(f₁−f₀)/(2f₁−f₀−f₂)]×h; Median = l + [(n/2−cf)/f]×h
Word problems: Train speed, age problems, rectangles. Identify: let x = ?, form equation, solve by factorisation or formula, reject negative root if needed.
Must know: sin 30°=½, cos 30°=√3/2, tan 45°=1, sin 90°=1, cos 0°=1. Memorise 5 identities and use them in proofs.
Formula list: CSA cylinder = 2πrh; CSA cone = πrl; SA sphere = 4πr²; Volume: πr²h (cyl), ⅓πr²h (cone), ⁴⁄₃πr³ (sphere).
Must know: AA, SSS, SAS similarity criteria. Ratio of areas = (ratio of sides)². Pythagoras theorem for right triangles.
Formulas: aₙ = a + (n−1)d; Sₙ = n/2 × [2a + (n−1)d] or n/2 × (a + l). Always identify a, d, n first.
Proof structure: Assume √2 = p/q (rational, HCF(p,q)=1) → 2 divides p → 2 divides p → 2 divides q → contradiction → irrational. This exact proof appears 4/6 years.
sin 0°=0, sin 30°=½, sin 45°=1/√2, sin 60°=√3/2, sin 90°=1
cos is reverse of sin (cos 0°=1, cos 90°=0)
tan = sin/cos: tan 30°=1/√3, tan 45°=1, tan 60°=√3
Identities: sin²θ+cos²θ=1 | sec²θ=1+tan²θ | cosec²θ=1+cot²θ
Mode: l + [(f₁−f₀)/(2f₁−f₀−f₂)] × h
Median: l + [(n/2 − cf) / f] × h
For ogive: Plot (upper boundary, cumulative frequency); find n/2 on y-axis; draw horizontal line to curve; drop vertical to x-axis = median.
Circle: A = πr², C = 2πr
Cylinder: V = πr²h, CSA = 2πrh
Cone: V = ⅓πr²h, CSA = πrl, l = √(r²+h²)
Sphere: V = ⁴⁄₃πr³, SA = 4πr²
Hemisphere: V = ⅔πr³, CSA = 2πr²
Dice: 1 die = 6 outcomes; 2 dice = 36 outcomes. P(sum=7) = 6/36 = 1/6. P(sum=12) = 1/36.
Bag problems: P = favourable/total. Always simplify.
✅ 3 statistics formulas (mean/mode/median) written
✅ 8 area/volume formulas memorised
✅ Irrational number proof written (√2 or √3)
✅ BPT theorem and application practised
✅ Quadratic factorisation — 5 examples
✅ AP nth term + sum formulas written
✅ 1 full mock paper timed in 3 hours
Section A MCQ (20 marks): 25 minutes
Section B SA-I 2-mark (10 marks): 15 minutes
Section C SA-II 3-mark (18 marks): 30 minutes
Section D LA 5-mark (20 marks): 40 minutes
Section E Case-based (12 marks): 25 minutes
Check + fill blanks: 5 minutes