Factor completely. If the polynomial cannot be factored, write ʺprime.ʺ
-$9 y ^ { 4 } - 49$
A) $\left( 3 y ^ { 2 } + 7 \right) ^ { 2 }$
B) $\left( 9 y ^ { 2 } + 1 \right) \left( y ^ { 2 } - 49 \right)$
C) $\left( 3 y ^ { 2 } + 7 \right) \left( 3 y ^ { 2 } - 7 \right)$
D) $\left( 3 y ^ { 2 } - 7 \right) ^ { 2 }$

Question

Quizplus · Accepted Answer

This polynomial can be factored using the difference of squares formula. Thus, we get:
$$9 y ^ { 4 } - 49 = (3 y ^2)^2 - 7^2 = (3 y ^ { 2 } + 7) \left( 3 y ^ { 2 } - 7 \right)$$ The other answer choices do not factor the polynomial correctly.

Factor Completely 9y4−499 y ^ { 4 } - 499y4−49 A) (3y2+7)2\left( 3 y ^ { 2 } + 7 \right) ^ { 2 }(3y2+7)2

Factor Completely $9 y ^ { 4 } - 49$ A) $\left( 3 y ^ { 2 } + 7 \right) ^ { 2 }$