NCERT Solutions
Class 10 Maths
Quadratic Equations

Ex. 4.2 Q1
Find the roots of the following quadratic equations by factorization:
(i) x2 – 3x – 10 = 0
(ii) 2x2 + x – 6 = 0
(iii) √2x2 + 7x + 5√2 = 0
(iv) 2x2 – x +1/8 = 0
(v) 100x2 – 20x + 1 = 0
(i) x2 – 3x – 10 = 0
=> x2 – 5x + 2x – 10 = 0
=> x(x - 5) + 2(x - 5) = 0
=> (x - 5)(x +2) = 0
=> x = -2, 5
Hence, the required roots are: -2 and 5
(ii) 2x2 + x – 6 = 0
=> 2x2 + 4x – 3x – 6 = 0
=> 2x(x + 2) – 3(x + 2) = 0
=> (x + 2)(2x - 3) = 0
=> x = -2, 3/2
Hence, the required roots are: -2 and 3/2
(iii) √2x2 + 7x + 5√2 = 0
=> √2x2 + 2x + 5x + 5√2 = 0
=> √2x2 + √2 * √2x + 5x + 5√2 = 0
=> √2x(x + √2) + 5(x + √2) = 0
=> (x + √2)(√2x + 5) = 0
=> x = -√2, -5/√2
Hence, the required roots are: -√2 and -5/√2
(iv) 2x2 – x + 1/8 = 0
=> (16x2 – 8x + 1)/8 = 0
=> 16x2 – 8x + 1 = 0
=> 16x2 – 4x – 4x + 1 = 0
=> 4x(4x - 1) – 1(4x - 1) = 0
=> (4x - 1)(4x - 1) = 0
=> x = 1/4, 1/4
Hence, the required roots are: 1/4 and 1/4
(v) 100x2 – 20x + 1 = 0
=> 100x2 – 10x – 10x + 1 = 0
=> 10x(10x - 1) – 1(10x - 1) = 0
=> (10x - 1)(10x - 1) = 0
=> x = 1/0, 1/10
Hence, the required roots are: 1/10 and 1/10