Solve.
-$25 y ^ { 4 } - 81$
A) $\left( 5 y ^ { 2 } - 9 \right) ^ { 2 }$
B) $\left( 25 y ^ { 2 } + 1 \right) \left( y ^ { 2 } - 81 \right)$
C) $\left( 5 y ^ { 2 } + 9 \right) \left( 5 y ^ { 2 } - 9 \right)$
D) $\left( 5 y ^ { 2 } + 9 \right) ^ { 2 }$

Question

Quizplus · Accepted Answer

The given expression can be factorized using the difference of squares formula as follows:
$$25y^4 - 81 = (5y^2)^2 - 9^2 = (5y^2 +9)(5y^2-9)$$
Therefore, the best choice is C.

Solve - 25y4−8125 y ^ { 4 } - 8125y4−81 A) (5y2−9)2\left( 5 y ^ { 2 } - 9 \right) ^ { 2 }(5y2−9)2

Solve
- $25 y ^ { 4 } - 81$ A) $\left( 5 y ^ { 2 } - 9 \right) ^ { 2 }$