Ask Question
3 April, 05:34

X (x+9) (x-1) = 72. find x

+3
Answers (1)
  1. 3 April, 07:01
    0
    X (x+9) (x-1) = 72

    lets expand the equation:

    (x^2 + 9x) (x - 1) = 72

    x^3 - x^2 + 9x^2 - 9x - 72 = 0

    x^3 + 8x^2 - 9x - 72 = 0

    and factorize again:

    x^2 (x + 8) - 9 (x + 8) = 0

    (x + 8) (x^2 - 9) = 0

    that is:

    (x + 8) (x + 3) (x - 3) = 0

    double check that x^2 - 9 = (x + 3) (x - 3), that is a subtraction of squares easily factorizable:

    So we have:

    (x + 8) (x + 3) (x - 3) = 0

    which solutions are:

    x = - 8, x = - 3, x = 3
Know the Answer?
Not Sure About the Answer?
Get an answer to your question ✅ “X (x+9) (x-1) = 72. find x ...” in 📙 Mathematics if there is no answer or all answers are wrong, use a search bar and try to find the answer among similar questions.
Search for Other Answers