When an algebraic equation contains fractions, you can use cross-multiplication to solve the equation. The following practice questions contain two equal fractions, where you need to cross-multiply to solve them.
Practice questions
- Rearrange the equation
to solve for x.
- Solve the equation
Answers and explanations
- x = –4Remove the fraction from the equation by cross-multiplying:
Multiply to remove the parentheses from the left side of the equation:
8x + 40 = –2x
At this point, you can solve for x:
- x = 5Remove the fractions from the equation by cross-multiplying:
Remove the parentheses from the left side of the equation by multiplying through by x; remove parentheses from the right side of the equation by FOILing:
4x2 – 7x = 4x2 – 10x + 6x – 15
Rearrange the equation:
4x2 – 7x – 4x2 + 10x – 6x = –15
Notice that the two x2 terms cancel each other out:
