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

1 Answer
Tony B
Dec 7, 2015

#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#

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#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.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

#color(blue)("Collecting terms")#

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

#2x^2+7x+5#

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