College Board · AP Precalculus

AP Precalculus: Functions Involving Parameters, Vectors, and Matrices — Practice Questions & Answers

Unit 4 widens the idea of a function beyond the familiar y as a function of x. You learn to describe motion and curves with parametric equations, handle implicitly defined relations and conic sections, represent quantities that have both size and direction with vectors, and organize and transform data with matrices. Although the College Board does not test this unit on the AP exam, it builds the foundation for calculus, linear algebra, and physics, so the concepts are well worth mastering.

74 practice questions available for this topic — here are 10 with full answers and explanations.

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Practice questions with answers

1 Multiple choice · Easy

Point A is at $(1,2)$ and point B is at $(4,6)$. What is the component form of the vector $\vec{AB}$?

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WhyTo find $\vec{AB}$ subtract the initial point from the terminal point: $\langle 4-1, 6-2\rangle = \langle 3,4\rangle$.
2 Multiple choice · Easy

What is the magnitude of the vector $\langle 3,4\rangle$?

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WhyThe magnitude is $\sqrt{3^{2}+4^{2}}=\sqrt{9+16}=\sqrt{25}=5$.
3 Multiple choice · Easy

Compute $\langle 2,3\rangle + \langle 1,-5\rangle$.

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WhyAdd corresponding components: $\langle 2+1, 3+(-5)\rangle = \langle 3,-2\rangle$.
4 Multiple choice · Easy

Compute the scalar multiple $3\langle 2,-1\rangle$.

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WhyMultiply each component by 3: $\langle 3\cdot 2, 3\cdot(-1)\rangle = \langle 6,-3\rangle$.
5 Multiple choice · Easy

What is the determinant of $\begin{pmatrix}2 & 3\\1 & 4\end{pmatrix}$?

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WhyThe determinant of a $2\times 2$ matrix is $ad-bc = (2)(4)-(3)(1) = 8-3 = 5$.
6 Multiple choice · Easy

Compute $\begin{pmatrix}1 & 2\\3 & 4\end{pmatrix} + \begin{pmatrix}0 & 1\\2 & 1\end{pmatrix}$.

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WhyAdd corresponding entries: $\begin{pmatrix}1+0 & 2+1\\3+2 & 4+1\end{pmatrix} = \begin{pmatrix}1 & 3\\5 & 5\end{pmatrix}$.
7 Fill in the blank · Easy

The magnitude of the vector $\langle 6,8\rangle$ is .

Answer: 10

WhyThe magnitude is $\sqrt{6^{2}+8^{2}}=\sqrt{36+64}=\sqrt{100}=10$.
8 Fill in the blank · Easy

In the $2\times 2$ identity matrix, the entries on the main diagonal equal 1 and all other entries equal .

Answer: 0

WhyThe identity matrix $\begin{pmatrix}1 & 0\\0 & 1\end{pmatrix}$ has 1's on the main diagonal and 0's elsewhere.
9 Fill in the blank · Easy

Compute the scalar multiple: $4\langle -1,2\rangle = \langle , \rangle$.

Answer: -4, 8

WhyMultiply each component by 4: $\langle 4(-1), 4(2)\rangle = \langle -4,8\rangle$.
10 Multiple choice · Medium

Compute the dot product $\langle 3,-2\rangle \cdot \langle 4,5\rangle$.

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WhyThe dot product is $(3)(4)+(-2)(5) = 12-10 = 2$.

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Key terms in Functions Involving Parameters, Vectors, and Matrices

Parameter: An independent variable, often $t$, used to express coordinates of points along a curve.
Parametric Function: A function in which $x$ and $y$ are each defined in terms of a parameter.
Parametric Equations: A pair of equations $x = f(t)$ and $y = g(t)$ describing a curve using a parameter.
Parametrization: The process of expressing a curve using a parameter.
Plane Curve: A set of points traced in the plane by parametric equations.
Orientation: The direction in which a parametric curve is traced as the parameter increases.
Direction of Motion: The path direction indicated by increasing parameter values along a parametric curve.
Eliminating the Parameter: Combining parametric equations to obtain a single equation in $x$ and $y$.

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