Factor the following trinomial assuming that all variables appearing as exponents represent positive integers. $x ^ { 2 a } + 10 x ^ { a } + 21$
A) $\left( x ^ { a } - 7 \right) \left( x ^ { a } + 3 \right)$
B) $\left( x ^ { a } + 7 \right) \left( x ^ { a } - 3 \right)$
C) $\left( x ^ { a } + 7 \right) \left( x ^ { a } + 3 \right)$
D) $\left( x ^ { a } - 7 \right) \left( x ^ { a } - 3 \right)$

Question

Quizplus · Accepted Answer

The trinomial can be factored by finding two numbers that multiply to 21 and add to 10, which are 7 and 3. Therefore, the correct factorization is $(x^a + 7)(x^a + 3)$.

Factor the Following Trinomial Assuming That All Variables Appearing as Exponents