ACT Preparation / Unit 7 ACT 0612 short lesson, about 20 seconds
Rationalizing a Denominator
Captions available
The idea
To clear a radical from a denominator, multiply top and bottom by the radical or, for a two-term denominator, by its conjugate, the same terms with the sign between them changed.
In practice
3/√2 = 3√2/2. 1/(1 + √3) = (1 − √3)/(1 − 3) = (√3 − 1)/2.
Where people slip
Multiply numerator and denominator by the same factor, so the value is unchanged.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
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