Advanced MathEasyPositive root of a factored equation
Advanced Math practice question
If (x − 3)(x + 8) = 0, what is the positive value of x that satisfies the equation?
Answer: 3
A product is zero when a factor is zero: x − 3 = 0 gives x = 3; x + 8 = 0 gives x = −8. The positive one is 3.
Common wrong answers
- If you answered 8
- 8 has the wrong sign: x + 8 = 0 means x = −8, which is negative anyway.
- If you answered -3
- −3 has the wrong sign: x − 3 = 0 means x = 3.
- If you answered -8
- −8 is a solution, but the question asks for the POSITIVE one.
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