ACT Preparation / Unit 11 ACT 1023 short lesson, about 20 seconds
The Remainder Theorem
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The idea
When a polynomial f(x) is divided by x − c, the remainder is f(c).
In practice
f(x) = x³ − 2x + 5 divided by x − 2 leaves remainder f(2) = 8 − 4 + 5 = 9.
Where people slip
Division by x + 3 uses c = −3, so the remainder is f(−3). Evaluating is often faster than dividing.
Your place on the trail
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Builds on
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