Common Algebra Mistakes
Example: Solving a Rational Equation

The Goal

Solve the equation for x:

goal


The Mistake

Find the algebra mistake:

mistake


Need a hint? Look carefully at the red part of the algebra:

mistake


The Correction

correction


An Explanation

The 2 in the numerator (left side) cannot just be moved to the right side - this is incorrect algebra.
To solve an equation in which a rational expression is equal to 0, simply set the numerator equal to 0 and solve. (A fraction is 0 precisely when the numerator is 0.)

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