Multiply: $$( 5 a + 3 ) ( 5 a + 7 )$$
A) $10 a ^ { 2 } + 15 a + 21$
B) $25 a ^ { 2 } + 50 a + 21$
C) $25 a ^ { 2 } + 35 a + 10$
D) $5 a ^ { 2 } + 38 a + 7$
E) $25 a ^ { 2 } + 20 a + 21$

Question

Quizplus · Accepted Answer

Use the distributive property to get: 
\begin{align*}
&(5a+3)(5a+7)\
&= 5a\cdot 5a + 5a\cdot 7 + 3\cdot 5a + 3 \cdot 7\
&= 25a^2 + 35a + 15a + 21\
&= 25a^2 + 50a + 21
\end{align*}

Multiply (5a+3)(5a+7)( 5 a + 3 ) ( 5 a + 7 )(5a+3)(5a+7)

Multiply $( 5 a + 3 ) ( 5 a + 7 )$