SOLUTION: Solve the equation: log2(x+7) + log2(x+8)=1

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Question 759924: Solve the equation: log2(x+7) + log2(x+8)=1
Found 2 solutions by stanbon, MathLover1:
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
Solve the equation: log2(x+7) + log2(x+8)=1
------------
log2[(x+7)(x+8)] = 1
-------------------
(x+7)(x+8) = 2
-------------------------
x^2 + 15x + 54 = 0
--------
(x+9)(x+6) = 0
Acceptable solution:
x = -6
==================
cheers,
Stan H.

Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!

log%282%2Cx%2B7%29+%2B+log%282%2Cx%2B8%29=1
log%282%2C%28%28x%2B7%29%28x%2B8%29%29%29=1
log%282%2C%28%28x%2B7%29%28x%2B8%29%29%29=1

log%28%28x%2B7%29%28x%2B8%29%29%2Flog%282%29=1
log%28%28x%2B7%29%28x%2B8%29%29=1%2Alog%282%29
log%28%28x%2B7%29%28x%2B8%29%29=log%282%29..if log same, then
%28x%2B7%29%28x%2B8%29=2
x%5E2%2B8x%2B7x%2B56=2
x%5E2%2B15x%2B56-2=0
x%5E2%2B15x%2B54=0
x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
x+=+%28-15+%2B-+sqrt%28+15%5E2-4%2A1%2A54+%29%29%2F%282%2A1%29+
x+=+%28-15+%2B-+sqrt%28+225-216+%29%29%2F2+
x+=+%28-15+%2B-+sqrt%28+9%29%29%2F2+
x+=+%28-15+%2B-+3%29%2F2+
solutions:
x+=+%28-15+%2B+3%29%2F2+
x+=+-12%2F2+
highlight%28x+=+-6%29+
or
x+=+%28-15+-+3%29%2F2+
x+=+-18%2F2+
highlight%28x+=+-9%29+