Math short but tricky
posted by Sabrina on .
Solve log.
2 log (x1)= log (x+1)
the answer is 3 but i don't know how to get it...Any one hint or suggestion will be greatly appreciated :)

2 log (x1)= log (x+1)
log[(x1)²] = log(x+1)
Take antilog:
(x1)²=x+1
Expand and solve quadratic:
x²3x=0
x(x3)=0
x=0 is not admissible as solution because log(01) is undefined.
The remaining answer is therefore x=3.