Question

Evaluate 9x^2y^−2 for x = –3 and y = 2.

a)9(−6)^0
b)1/144
c)20 1/4
d)324

Answer 1

c)20 1/4

Explanation:

`9x^(2)y^(-2)`

If We replace x by -3 and y by 2 we get :

`9\left( -3\right)^(2) \left( 2\right)^(-2)`

Or we have :

`\left( -3\right)^(2) =9\ \text{and} \ \left( 2\right)^(-2) =(1)/(2^(2)) =(1)/(4)`

then

`9\left( -3\right)^(2) \left( 2\right)^(-2)=9*9*(1)/(4) = (81)/(4)`

on the other hand :

`(81)/(4) =(80+1)/(4) =(80)/(4) +(1)/(4) =20+(1)/(4)=20(1)/(4)`