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5 votes
What number would be added to both sides in order to complete the square when solving x^2+8x=9?

A.16
B.18
C.64
D.81

User Jschr
by
7.8k points

2 Answers

0 votes
A. 16
1/2(MT)^2
1/2(8)^2
=4^2
=16
User Jimmymcnulty
by
8.2k points
3 votes
You can figure this out if you just look at (x+a)^2 = x^2 + 2ax + a^2. See, the constant term, a^2, is the coefficient of x (2a), divided by 2 (2a/2=a), and then squared (a^2)

So you equation has 8x. 8/2 = 4, and 4^2 = 16. So the answer is A.
User Robert Stiffler
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7.9k points

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