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

Answer:

c)20 1/4

Step-by-step 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 :

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

then

$9\left( -3\right)^{2} \left( 2\right)^{-2}=9\times9\times\frac{1}{4} = \frac{81}{4}$

on the other hand :

$\frac{81}{4} =\frac{80+1}{4} =\frac{80}{4} +\frac{1}{4} =20+\frac{1}{4}=20\frac{1}{4}$