Question

Use a suitable identity to get each of the following products.

(i) (x + 3) (x + 3) 

(ii) (2y + 5) (2y + 5)

(iii) (2a − 7) (2a − 7)

Answer 1

The products will be as follows.

(i) (x + 3) (x + 3)  = (x + 3)²

= (x)² + 2(x) (3) + (3)² [(a + b)²  = a² + 2ab + b²]

= x² + 6x + 9

(ii) (2y + 5) (2y + 5)  = (2y + 5)²

= (2y)² + 2(2y) (5) + (5)² [(a + b)² = a² + 2ab + b²]

= 4y² + 20y + 25

(iii) (2a − 7) (2a − 7)  = (2a − 7)²

= (2a)² − 2(2a) (7) + (7)² [(a − b)² = a² − 2ab + b²]

= 4a² − 28a + 49