Question

(x+7)(x+7)
(3x + 1) (3x-8)

Answer 1

Question:-

Solve:-

(x+7)(x+7)

(3x + 1) (3x-8)

Answer:-

➡️Using identity

(a+b)² = a² + 2ab + b²

Here, a= x

b= 7

(x+7)(x+7)

=(x+7)²

= (x)² + 2×x×7 + 7²

= x² + 14x + 49

➡️Using Identity

(x+a)(x-b) = x² + (a+b)x - ab

Here , x = 3x

a = 1

b = 8

(3x+1)(3x-8)

= (3x)² +(1+8)3x - (1×8)

= 9x² + 27x -8

Formula to be remembered:-

▪︎(a+b)² = a² + 2ab + b²

▪︎(x+a)(x+b) = x² + (a+b)x + ab

▪︎(x+a)(x-b) = x² + (a+b)x - ab

▪︎(a-b)² = a² - 2ab + b²

▪︎a² - b² = (a+b)(a-b)

Answer 2

i)=x^2 + 7x + 7x + 7×7

=x^2+ 14x + 49

ii)=3x^2 - 3x × 8 + 3x × 1 - 8×1

=3x^2 - 24x + 3x + 8 - 8

= 3x^2+ 21+0