ACT Preparation / Unit 8 ACT 0719 short lesson, about 20 seconds
Adding Rational Expressions
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The idea
To add or subtract rational expressions, rewrite them over a common denominator, the least common denominator, then combine the numerators.
In practice
2/x + 3/(x + 1) = (2(x + 1) + 3x)/(x(x + 1)) = (5x + 2)/(x(x + 1)).
Where people slip
Never add denominators: 1/2 + 1/3 is 5/6, not 2/5. When subtracting, the minus sign applies to every term of the second numerator.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
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