You can
put this solution on YOUR website!
You do a problem like this by "solving it backwards",
starting with the solution and going backward to the problem.
If you had solved such an equation and ended up with
x = 7 and x = -3
then before that you would have had
x - 7 = 0 and x + 3 = 0
then before that you would have had
(x - 7)(x + 3) = 0
then before that you would have had
x² - 4x - 21 = 0
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Check it by solving forward:
x² - 4x - 21 = 0
(x - 7)(x + 3) = 0
x - 7 = 0 and x + 3 = 0
x = 7 and x = -3
It checks when solved forward, so the correct
equation is
x² - 4x - 21 = 0
Edwin
