Question

Find the roots of the polynomial equation. x^2 – x – 72 = 0 Question 1 options: A) 9 and –8 B) –6 and 6 C) –2 and 16 D) –9 and 8

Answer 1

                    x² - x - 72 = 0
          x² - 9x + 8x - 72 = 0
x(x) - x(9) + 8(x) - 8(9) = 0
         x(x - 9) + 8(x - 9) = 0
                (x + 8)(x - 9) = 0
x + 8 = 0      or      x - 9 = 0
    - 8  - 8                 + 9 + 9
      x = -8        or        x = 9

The answer is A.