Complete question is;
Tiothy evaluated the expression using x = 3 and y = –4. The expression is (xy^(-2))/(3x²y^(−4))
1. (1/3)x^(−1)(y²) 2. ((1/3)^(3−1))(−4²) 3. (1/3)(1/3)(−4)² 4. (1/3)(1/3)(−16) 5. −16/9 Analyze Timothy's steps. Is he correct? If not, why not?
A) Yes, he is correct.
B) No, he needed to add the exponents when he simplified the powers of the same base.
C) No, he needed to multiply 3 and –1 instead of creating a positive exponent in a fraction.
D) No, his value of (negative 4) squared should be positive because an even exponent indicates a positive value.
Answer:
D) No, his value of (negative 4) squared should be positive because an even exponent indicates a positive value.
Explanation:
The expression is;
(xy^(-2))/(3x²y^(−4))
Simplifying this using law of indices gives;
⅓(x^(1 - 2)) × (y^(-2 -(-4))
This gives;
= (⅓x^(-1)) × y²
= ⅓ × (1/x) × y²
We are told that x = 3 and y = –4, thus;
= ⅓ × ⅓ × (-4)²
Square of a negative number is positive, thus (-4)² = 16
Thus;
⅓ × ⅓ × (-4)² = 16/9
Looking at the answer Timothy got, it's clear he made a mistake of not getting a positive number when he squared -4.
Thus,option D is the correct answer.