How do you solve log _x 8 = -3logx8=3?

1 Answer
Dec 4, 2015

x=1/2x=12

Explanation:

log_x 8=-3logx8=3
=>log_x 2^3=-3logx23=3
3log_x 2=-33logx2=3 (The logarithm of the 3^(rd)3rd power of a number is 33 times the logarithm of the number itself)
Divide both side into 1/313, in order to simplify left side:
1/3*3log_x 2=1/3*(-3)133logx2=13(3)
=>log_x 2=-1logx2=1
=>x^-1=2x1=2 (definition of logarithm)
Multiply both side by xx:
x*x^-1=x*2xx1=x2
=>2x=x^02x=x0 (If we take the product of two exponentials with the same nonzero base, we simply add the exponents)
Multiply both side by 1/212, in order to simplify left side:
1/2*2x=1/2*1122x=121
x=1/2x=12