Answer:

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:
