Vectors and matrices on the ACT Mathematics test covers vector length, matrix equality, and using given entries to find a related value.
A student has to compute magnitude from components, recognize when two matrices are the same, and combine named entries after a simple operation. The exam tends to ask for the magnitude of a vector, which matrix equals a given expression, or a value such as a plus b.
Answer choices are usually numbers or small matrices. Common traps include swapping components, treating matrix multiplication as commutative, and choosing a matrix with the right entries in the wrong order.
Sample questions
Pick an answer to see whether it is right — nothing is saved, and nothing needs an account.
Question 1Easier
What is the magnitude of the vector ⟨−6,8⟩?
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Answer: B — 10
Magnitude is (−6)2+82=36+64=100=10.
Question 2Easier
Which of the following matrices is equal to 3[2005]−[3012]?
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Answer: A — [30−113]
Scale first: 3[2005]=[60015]. Subtracting entry by entry gives 6−3=3,0−1=−1,0−0=0, and 15−2=13.
Question 3Mid
If [1021][ab]=[73], what is the value of a+b?
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Answer: C — 4
The second row gives b=3. Then a+2b=7, so a=1 and a+b=4.
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