# How do you simplify (x^2 + 7x – 4) + (x^2 + 9)?

Dec 7, 2015

$2 {x}^{2} + 7 x + 5$

#### Explanation:

There is no multiplication or division of the brackets so you simply remove the brackets, collect like terms and do the arithmetic (math)

$\textcolor{b l u e}{\text{Removing the brackets}}$

${x}^{2} + 7 x - 4 + {x}^{2} + 9$

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$\textcolor{b r o w n}{\text{An extra thought:}}$
If we had been given $\left({x}^{2} + 7 x - 4\right) - \left({x}^{2} + 9\right)$
Then the minus sign in front of $\left({x}^{2} + 9\right)$ would mean that we have to change the sign of everything inside that right hand bracket. Suppose that had been the case, then we would have had: ${x}^{2} + 7 x - 4 \textcolor{b l u e}{- {x}^{2} - 9}$ instead.
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$\textcolor{b l u e}{\text{Collecting terms}}$

${x}^{2} + {x}^{2} + 7 x + 9 - 4$

$2 {x}^{2} + 7 x + 5$