Solve for x x squared plus 4x minus 21 equals 0

x = -7 and x = 3

Step-by-step explanation:

x² + 4x - 21 = 0 factors as follows:  (x + 7)(x - 3) = 0.

Then x = -7 and x = 3.

Step-by-step explanation:

We have the following quadratic equation

To solve the equation we must factor it.

To factor the equation we must find 2 numbers b and c that when adding them, you obtain as result 4 () and when multiplying them, you obtain as result -21 ().

Then the polynomial will be factored in the following way:

You can verify that the numbers that meet this condition are:

So

Finally the solutions are: