Question

Timothy evaluated the expression using x = 3 and y = –4. xy-2 3x2y−4 1. (1 3 )x−1y2 2. (1 3 )3−1(−4)2 3. (1 3 )(1 31 )(−4)2 4. (1 3 )(1 3 )(−16) 5. −16 9

Answer 1

If this is for E2020 the answer is
 D)No, his value of  should be positive because an even exponent indicates a positive value. 
thats why it was wrong

Answer 2

Answer with explanation:

We have to evaluate the expression for, x=3 and y= -4 .The expression is

    $\rightarrow x \times y^{-2} \times 3 \times x^2 \times y^{-4}\\\\ \rightarrow 3 x^{1+2} \times y^{-2-4}\\\\ \rightarrow 3 x^{3} \times y^{-6}\\\\=3 (3)^3 \times (-4)^{-6}\\\\=\frac{3^4}{4^6}\\\\ \text{used}x^a \times x^b=x^{a+b}\\\\x^{-a}=\frac{1}{x^a}$