Math CentralQuandaries & Queries


Question from Rebecca:

-2 (a + 4) = 18
how do i do this with showing it distributive property ( symbolically)
Thank you!

Hi Rebecca,

I see two methods to solve for $a.$

First method:
Divide both sides by -2 to get
\[a + 4 = \frac{18}{-2} = -9.\]
Finally add -4 to each side.
Second method:
Use the distributive law to write $-2(a + 4)$ as $-2a - 8.$ and hence the equation becomes $-2a - 8 = 18.$

I hope this helps,

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