1963 TMTA High School Algebra I Contest Problem 10

Problem

Which of the following is true?

$\text{(A)} \quad a^3a^4 = (a^3)^7$

$\text{(B)} \quad a^3 + a^4 = a^7$

$\text{(C)} \quad \frac{(a+b)^3}{a^3} = b^3$

$\text{(D)} \quad a^3a^4 = a^12$

$\text{(E)} \quad \frac{(ab)^3}{a^3} = b^3$

Solution

Reviewing the rules of exponents, we see that A, B, and E are false. Expanding C and E, we find that $\boxed{\text{(E)}}$ is true.

See Also

1963 TMTA High School Mathematics Contests (Problems)
Preceded by
Problem 9
TMTA High School Mathematics Contest Past Problems/Solutions Followed by
Problem 11