Question

I don’t know how to solve the equation

Answer 1

To solve this equation we have to factor.
We are looking for 2 numbers with a sum of -3, and multiplied they have to be -28. These numbers are -7 and 4.

So:
${x}^{2} - 3x - 28 = 0$
$(x - 7)(x + 4) = 0$
$x - 7 = 0 \: \: \: \: x + 4 = 0$
$x = 7 \: \: \: \: x = - 4$