SAT Math · Equivalent expressions · medium

When the polynomial x³ + 4x² - 2x + 1 is divided by x - 1, what is the remainder?

When the polynomial x3+4x2−2x+1x^3 + 4x^2 - 2x + 1 is divided by x−1x - 1, what is the remainder?

Answer and explanation

Answer: B: 4

By the remainder theorem, dividing by x−1x - 1 leaves the remainder p(1)p(1). Compute: p(1)=13+4(1)2−2(1)+1=1+4−2+1=4p(1) = 1^3 + 4(1)^2 - 2(1) + 1 = 1 + 4 - 2 + 1 = 4, choice B. Synthetic division with coefficients 1, 4, −2-2, 1 gives 1, 5, 3, 4, with remainder 4. Choice A (1) is the constant term or the root. Choice C (3) is the last coefficient in the quotient, one step before the remainder. Choice D (−4-4) results from evaluating at x=−1x = -1, which would be the divisor x+1x + 1. Evaluate at the value that makes the divisor zero.

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