Question

How would you solve?
log x=log(x^2-12) ?

Answer 1

\[\log x=\log(x^2-12)\rightarrow x=x^2-12\rightarrow x^2-x-12=0=(x+4)(x-3)\]So x=3 (can't be -4 due to domain restrictions on the log function)

Answer 2

Actually, neither solution is any good. No solution.

Answer 3

Luis, you did the same calculation I did, but neither of those solutions meet the specifications of the problem. If x=3, the RHS has a negative number in the argument of the log. If x=-4, the same problem on the LHS. No solution.

Answer 4

you didn't factor x^2-x-12 properly. the answer is x=4

Answer 5

luis did it right

Answer 6

we know -4 + 3 is -1 and -4 * 3 is -12
so X^2-X-12=X^2 -4x+3x- 4 *3
= X(X-4)+3(X-4)
=(X-4)(X+3)

Answer 7

Yep. Epic fail.................