Common Algebra Mistakes
Example: Solving an Exponential Equation
Solve the following equation for t:
Find the algebra mistake:
(Roll the mouse over the algebra to see a hint in red)
(Roll the mouse over the area above to see the correction in blue)
The rules of logarithms were used incorrectly in the first step - the t cannot be pulled in front of the 2000 since 2000 was not raised to the power t. "The Correction" shows how the rules could have been applied. The second step in "The Mistake" is a mystery; perhaps the first step was ignored and from the initial equation the student divided incorrectly. Take care with the simple things.
Notice how this solution isolates t one step at a time, from the outside to the inside. First divide by 2000. This let's us undo the exponential by taking the natural logarithm of both sides. Finally, divide by 0.06, the remaining coefficient of t.
Home Page |
Common Algebra Mistakes |