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

Question

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

anonymous · Answer

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

anonymous · Answer

Actually, neither solution is any good.  No solution.

anonymous · Answer

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.

anonymous · Answer

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

anonymous · Answer

luis did it right

anonymous · Answer

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)

anonymous · Answer

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