SOLUTION: Solve for x: log base4 (x) + log base 4 (x+3) = log base4 (8)

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Question 507914: Solve for x:
log base4 (x) + log base 4 (x+3) = log base4 (8)

Answer by lwsshak3(11628) About Me  (Show Source):
You can put this solution on YOUR website!
Solve for x:
log base4 (x) + log base 4 (x+3) = log base4 (8)
**
log4(x)+ log4(x+3)-log4(8)=0
place under a single log=0
log4[(x(x+3)/8)]=0
convert to exponential form: base(4) raised to log of the number(0)=number(x(x+3)/8)
4^0=(x(x+3)/8)=1
(x^2+3x)/8=1
x^2+3x=8
x^2+3x-8=0
use following quadratic formula to solve:
..
x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
..
a=1, b=3, c=-8
x=[-3±√(3^2-4*1*-8]/2*1
x=[-3±√9+32]/2
x=-3±√41/2
x=-3±6.4031/2
x=-4.7016 (reject, (x+3)>0)
or
x=1.7016 (ans)