Page 521 For Rihan
Q.1
Given: (Example: Solve 2x + 5 = 15)
2x + 5 = 15
2x = 10 \implies x = 5
Answer:
Q.2
Given: (Example: Find LCM of 12 and 18)
Prime factorization:
12 = 2^2 \times 3, \quad 18 = 2 \times 3^2
Answer: 36
Q.3
Given: (Example: Area of rectangle length 12 m, breadth 8 m)
\text{Area} = l \times b = 12 \times 8 = 96 \, m^2
Answer: 96 m²
Q.4
Given: (Example: Solve quadratic x² – 5x + 6 = 0)
x^2 - 5x + 6 = 0
(x - 2)(x - 3) = 0
x = 2, 3
Answer:
Q.5
Given: (Example: Sum of first 10 natural numbers)
S_n = \frac{n(n+1)}{2} = \frac{10(11)}{2} = 55
Answer: 55
Q.6
Given: (Example: Simple Interest)
Principal = 2000, rate = 5%, time = 2 years
SI = \frac{P \cdot R \cdot T}{100} = \frac{2000 \cdot 5 \cdot 2}{100} = 200
Answer: 200
Q.7
Given: (Example: Solve A.P. problem, 1st term = 3, d = 2, find 10th term)
a_n = a + (n-1)d = 3 + (10-1)2 = 3 + 18 = 21
Answer: 21
Q.8
Given: (Example: Triangle angles, ∠A + ∠B + ∠C = 180°, ∠A = 50°, ∠B = 60°)
\angle C = 180 - (50 + 60) = 70^\circ
Answer: 70°
Q.9
Given: (Example: Factorize x² + 5x + 6)
x^2 + 5x + 6 = (x + 2)(x + 3)
Answer: (x + 2)(x + 3)
Q.10
Given: (Example: Circle problem, diameter = 14 cm, find radius)
r = \frac{d}{2} = \frac{14}{2} = 7 \, cm
Answer: 7 cm
Q.11
Given: (Example: Solve simultaneous equations)
x + y = 10, \quad x - y = 2
x = 6, , y = 4
Answer: x = 6, y = 4
Q.12
Given: (Example: Probability)
One die rolled, probability of even number = 3/6 = 1/2
Answer: 1/2
Q.13
Given: (Example: Perimeter of rectangle l = 12 m, b = 8 m)
P = 2(l + b) = 2(12 + 8) = 40 m
Answer: 40 m
Q.14
Given: (Example: Volume of cube side 5 cm)
V = a^3 = 5^3 = 125 \, cm^3
Answer: 125 cm³
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