Question

Which of the following quadratic equations has the solution set (-20,9)? SELECT ALL THAT APPLY

A. (x+20)(x-9)=0
B. (x-20)(x+9)=0
C. (x-5)(x-4)=0
D. x^2-9x+20=0
E. x^2-11x+180=0
F. x^2+11x-180

Answer 1

A, F

Explanation:

When the roots are a and b, the factors are (x-a) and (x-b). For roots -20 and 9, the factors are (x+20) and (x-9).

This selects answer A and eliminates choices B and C.

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Multiplying the two factors gives ...

... (x +20)(x -9) = x² +11x -180

This selects answer F and eliminates choices D and E.