7C

Equations with fractions

Solving equations with algebraic fractions by multiplying both sides, including fractions on both sides and cross-multiplying.

Clearing fractions

Example 1●●

Solve $\dfrac{x + 4}{3} = 5$.

$x + 4 = 15$
Multiply both sides by 3
$x = 11$
Example 2●●

Solve $\dfrac{x}{3} + 2 = 6$.

$\dfrac{x}{3} = 4$
$x = 12$

A fraction on each side

Example 3●●●

Solve $\dfrac{x + 1}{2} = \dfrac{x + 5}{4}$.

$2(x + 1) = x + 5$
Multiply both sides by 4 (the LCD)
$2x + 2 = x + 5$, so $x = 3$
Flashcards
$dfrac{x}{5} = 3$
$x = 15$
Fraction on each side
Multiply both sides by the lowest common denominator.
$dfrac{x - 1}{2} = 4$
$x = 9$
Practice
  1. Solve $\dfrac{x + 4}{3} = 5$.

  2. Solve $\dfrac{x}{3} + 2 = 6$.

  3. Solve $\dfrac{x + 1}{2} = \dfrac{x + 5}{4}$.

  4. Solve $\dfrac{x - 1}{2} = 4$.

  5. Solve $\dfrac{3x}{5} = 6$.

  6. Solve $\dfrac{x}{2} - 1 = -4$.

  7. Solve $\dfrac{2x + 1}{5} = 3$.

  8. Solve $\dfrac{x}{2} = \dfrac{x}{3} + 1$.

More questions

New numbers every time. Keep going until you get five in a row.

Formula sheet