Multiply: $$( 3 p + 7 ) ( 3 p - 7 )$$
A) $9 p ^ { 2 } - 49$
B) $9 p ^ { 2 } + 21 p - 49$
C) $9 p ^ { 2 } + 49$
D) $9 p ^ { 2 } - 14$
E) $9 p ^ { 2 } + 21 p + 49$

Question

Quizplus · Accepted Answer

Use the formula for the difference of squares:
$$(a+b)(a-b)=a^2-b^2$$
In this case, let $a=3p$ and $b=7$, then we get:
$$(3p+7)(3p-7)= (3p)^2 - 7^2 = 9p^2 - 49$$
Therefore, the answer is $\boxed{	extbf{(A)}\ 9 p ^ { 2 } - 49}$.

Multiply (3p+7)(3p−7)( 3 p + 7 ) ( 3 p - 7 )(3p+7)(3p−7)

Multiply $( 3 p + 7 ) ( 3 p - 7 )$