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14 votes
14 votes
complete the square: $4x^2 5x 2$. enter your answer in the form $a(x u)^2 v$, where $a,$ $u,$ and $v$ are replaced by numbers.

User Lunette
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1 Answer

8 votes
8 votes

I assume the missing symbols are plus signs, so we have


4x^2 + 5x + 2 = 4\left(x^2 + \frac54x\right) + 2 \\\\ ~~~~~~~~ = 4 \left(x^2 + \frac54x + \left(\frac58\right)^2 - \left(\frac58\right)^2\right) + 2 \\\\ ~~~~~~~~ = 4 \left(x^2 + \frac54x + \left(\frac58\right)^2\right) - (25)/(16) + 2 \\\\ ~~~~~~~~ = \boxed{4 \left(x + \frac58\right)^2 + \frac7{16}}

so that
a=4,
u=\frac58 and
v=\frac7{16}.

User Alessandro Benassi
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2.2k points