Question

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

Answer 1

`2x^2+7x+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)

`color(blue)("Removing the brackets")`

`x^2+7x-4+x^2+9`

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`color(brown)("An extra thought:")`
If we had been given `(x^2+7x-4) -(x^2+9)`
Then the minus sign in front of `(x^2+9)` 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+7x-4color(blue)(-x^2-9)` instead.
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`color(blue)("Collecting terms")`

`x^2+x^2 +7x+9-4`

`2x^2+7x+5`