PSAT Math Multiple-Choice Question 464: Answer and Explanation

Question: 464

If (x, y) is a solution to the system of equations shown here, what is the value of x² ?

• A. 6
• B. 36
• C. 144
• D. 1,296

Correct Answer: B

Explanation:

B

Difficulty: Medium

Getting to the Answer: Even though one of the equations in this system is not linear, you can still solve the system using substitution. You already know that y is equal to 3x, so substitute 3x for y in the second equation. Don't forget that when you square 3x, you must square both the coefficient and the variable:

The question asks for the value of x², not x, so there is no need to take the square root of 36 to find the value of x. Choice (B) is correct.