Question

Find the value of c² +d² if c+d= 12 and c-d =4 , by using identity.​

Answer 1

Given,

c + d = 12 ••••••••• (1)

c - d = 4 ••••••••••• (2)

To Find : c² + d²

On adding (1) + (2)

c + d + c - d = 12 + 4

2c = 16

c = 8

Putting the value of 'c' in equation (1)

8 + d = 12

d = 12 - 8 = 4

Now calculating c² + d²

c² + d² = (c + d)² - 2cd

8² + 4² = (8 + 4)² - 2×8×4

= (12)² -64

= 144 - 64 = 80