The product of $a$ and $b$ is,
\[\begin{split}
a\times b &= (2x-3)(2x+5)\\
&= \{2x+(-3)\}(2x+5)\\
&= (2x)(2x)+(5-3)2x-15\\
&= 16+8-15\\
&= 9
\end{split}\]
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- Sat Oct 15, 2016 10:05 pm
- Forum: Junior Level
- Topic: Answer the question
- Replies: 2
- Views: 8155