Question

use identity to find (×+9)(×+b)=×^2+(a+b)×+ab (7×+2)7×-2)​

Answer 1

Answer:

If a-b = 7 and ab=9, then what is a^2+b^2?

a-b = 7 then

a = 7+b —————— (1)

ab=9 then

putting ‘a’ value as above

7+b (b) = 9

7+b^2 = 9 then b^2 = 9–2 which means, b^2 = 2 ————— (2)

Now apply this to a^2+b^2

Let’s imagine a^2+b^2 = 0 then,

a^2+2 = 0 [applying the value of (2) for b^2] then,

a^2 = -2 ———————- (3)

Now we have values of a^2 and b^2, lets apply to a^2+b^2

(-2) + 2 = 0

Proved.