SAT Math Multiple Choice Question 480: Answer and Explanation
15. If the equation has solutions x1 and x2, what is the product of x1 and x2?
- A. –45
- B. –15
- C. –5
- D. 3
Correct Answer: A
Category: Passport to Advanced Math / Quadratics
Strategic Advice: This is a quadratic equation, so you need one side to equal 0 and then, best-case scenario, you'll be able to factor. If not, you can rely on the quadratic formula.
Getting to the Answer: First, subtract 3 from both sides of the equation. Then multiply everything by 9 to clear the fractions.
Each number in the equation is divisible by 2, so factor out a 2 and go from there.
The solutions are –15 and 3, but be careful! The question asks for the product of the solutions, so the correct answer is (–15)(3) = –45.