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Rational Root Theorem Worksheet with Answers – Precalculus (Free PDF)

Last updated: October 22, 2026 · Written by the Math Made Easy math teachers

Precalculus Math Worksheets – Mathbot, the Math Made Easy robot coach, with free printable worksheets for Precalculus

Looking for a rational root theorem worksheet with answers PDF? Then this Precalculus worksheet on Polynomial and Rational Functions: Zeros and Asymptotes gives problems ranked from easy to hard. These 20 problems cover the Rational Root Theorem, complex and conjugate zeros, end behavior, slant asymptotes and sign-chart inequalities. They train standards A-APR.B.2, A-APR.B.3, F-IF.C.7c, F-IF.C.7d and N-CN.C.9.

The last six problems use crates, kit costs, a thrown ball and a medicine dose, so every inequality and asymptote has a real meaning.

Standards: A-APR.B.2, A-APR.B.3, F-IF.C.7c, F-IF.C.7d, N-CN.C.9 · Level: Grade 12 Precalculus

Problem 2 End Behavior from the Leading Term ★★★

Describe the end behavior of each function in words. (a) f(x) = −2x5 + 7x − 1   (b) g(x) = 4x4 − x3   (c) h(x) = −x6 + 9x2

Problem 3 Conjugate Zeros ★★★

Suppose P has degree 4 and real coefficients, and two of its zeros are 2 − 5i and −1 + i. Name the remaining two zeros.

Problem 4 Classify the Asymptote Type ★★★

Without graphing, state whether each function has a horizontal asymptote, a slant asymptote or neither, and give its equation. (a) x3 + 1x2 − 4   (b) 3x2 + 1x2 − 9   (c) x + 5x2 + 2

Problem 5 Read a Sign Chart ★★★

The sign chart shows the sign of Q(x) = (x + 5)(x − 1)(x − 4) on each interval. Solve Q(x) > 0.

−514−+−+
Signs of Q(x).

Problem 6 Count the Complex Zeros ★★★

Let P(x) = (x − 4)3(x2 + 9)(x + 1). Give the degree, list all complex zeros counting repeats, and confirm the Fundamental Theorem of Algebra count.

Problem 7 Find All Zeros with Candidates ★★★

Find all zeros of P(x) = 2x3 + 7x2 − 5x − 4.

Problem 8 Real and Complex Zeros Together ★★★

Determine every zero, real and non-real, of P(x) = x3 + x2 + 4x + 30.

Problem 9 Build a Polynomial from Zeros ★★★

Construct a monic cubic with real coefficients whose zeros include 5 and 3 − 2i. Multiply out the factors.

Problem 10 Slant Asymptote by Division ★★★

Find the slant asymptote and the vertical asymptote of f(x) = 3x2 − x + 4x − 2.

Problem 11 Identify Asymptotes on a Graph ★★★

The graph shows f(x) = x2 − 4x + 1x − 3 with two dashed asymptotes. Write their equations, then confirm the slant one by division.

−4−2246810−8−44812
Rational function with two dashed asymptotes.

Problem 12 Quadratic Inequality ★★★

The graph of y = 2x2 − 5x − 12 is shown. Solve 2x2 − 5x − 12 ≤ 0 algebraically and give the solution set as an interval.

−3−2−1123456−20−15−10−551015
Graph of y = 2x2 − 5x − 12.

Problem 13 Rational Inequality with a Constant ★★★

Solve x + 1x − 5 ≤ 2.

Problem 14 Zeros and Multiplicity from a Graph ★★★

The graph is a polynomial with leading coefficient −1 and degree 4. It meets the x-axis at −2, 1 and 3 and touches (does not cross) at 1. Find each zero’s multiplicity, describe the end behavior, and write a possible equation.

−3−2−1123−30−20−10102030
Graph of a degree-4 polynomial.

Problem 15 Solve a Quartic over the Complex Numbers ★★★

Solve x4 − x2 − 12 = 0 over the complex numbers.

Problem 16 Dimensions of a Crate ★★★

A crate has width x feet, length x + 2 feet and height x − 1 feet. Its volume is 72 cubic feet. Set up the equation, find the real value of x with the Rational Root Theorem, and show that the other two solutions are not real.

Problem 17 Average Cost and Its Asymptote ★★★

A robotics club builds n kits for a total cost of 2n2 + 30n + 450 dollars. The average cost per kit is A(n) = 2n2 + 30n + 450n. Find the slant asymptote, then find how many kits (whole numbers) keep the average cost at or below $110.

Problem 18 Ball Above a Height ★★★

A ball is thrown so that its height is h(t) = −16t2 + 48t + 64 feet after t seconds. For how long is it above 32 feet before it lands? Give the exact interval and a decimal approximation.

Problem 19 Medicine Concentration Window ★★★

The concentration of a medicine in the blood is C(t) = 40tt2 + 16 mg/L after t hours. When is the concentration at least 2.5 mg/L? Give exact endpoints and approximations.

Problem 20 Use a Given Zero to Solve a Quartic ★★★

Given that 2i is a zero of P(x) = x4 − 2x3 + 6x2 − 8x + 8, find every zero.

View the Rational Root Theorem worksheet answer key