SAT Math · Equivalent expressions · medium

When the polynomial x³ + 3x² - x + 2 is divided by x - 2, what is the remainder?

When the polynomial x3+3x2−x+2x^3 + 3x^2 - x + 2 is divided by x−2x - 2, what is the remainder?

Answer and explanation

Answer: D: 20

By the remainder theorem, dividing a polynomial p(x)p(x) by x−2x - 2 leaves the remainder p(2)p(2). Compute p(2)=23+3(2)2−2+2=8+12−2+2=20p(2) = 2^3 + 3(2)^2 - 2 + 2 = 8 + 12 - 2 + 2 = 20, choice D. Synthetic division with coefficients 1, 3, −1-1, 2 gives 1, 5, 9, 20, confirming the remainder. Choice A (2) is the root value used for the divisor. Choice B (14) comes from a sign slip in the last term, 8+12−2−48 + 12 - 2 - 4. Choice C (−20-20) has the wrong sign and does not match p(2)p(2). Evaluate at the root of x−2x - 2, namely +2+2.

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