The Goal

Solve the following equation for y:

The Mistake

Find the algebra mistake:

(Roll the mouse over the algebra to see a hint in red)

The Correction

(Roll the mouse over the area above to see the correction in blue)

An Explanation

Instead of dividing by -4 the student added 4 to both sides. The mistake has nothing to do with logarithms. The correct step is:

Check the following complete solution (use the logarithm rules ln(a/b) = ln(a) - ln(b) and ln(1) = 0):