Multiple choice

Which of the following is a root of the quadratic equation x2 - 9x + 20 = 0?

  1. -4

  2. -8

  3. 4

  4. 3
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Factoring x^2 - 9x + 20 = 0 gives (x-4)(x-5) = 0. The roots are 4 and 5.

AI explanation

To find the roots, factor the quadratic equation x squared minus 9x plus 20 equals 0 by splitting the middle term. The term negative 9x splits into negative 4x and negative 5x, yielding the factors (x minus 4) and (x minus 5). Setting these factors to zero gives the roots as 4 and 5, so 4 is a valid root.

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