Question

What expression is not equivalent to 1/343

Answer 1

1 / 343
This is just equal to 
1 / 7^3 = 7^-3

A. 7^-1 * 7^-2 = 7^(-1 + -2) = 7^-3
B. 7^7 * 7^-10 = 7^( 7+ -10) = 7^-3
C. 7^-2 * 7^-5 = 7^(-2 + -5) = 7^-7
D. 7^-5 * 7^2 = 7^(-5 + 2) = 7^-3

So the correct answer is letter C. 7^-2 * 7^-5