# How do you solve x^2- 3x - 28 = 0?

Jun 28, 2015

The solutions are:
color(blue)(x=-4 , x=7

#### Explanation:

${x}^{2} - 3 x - 28 = 0$

We can first factorise this expression by splitting the middle term and then find the solutions:

$= {x}^{2} \textcolor{b l u e}{- 7 x + 4 x} - 28 = 0$
$= x \left(x - 7\right) + 4 \left(x - 7\right) = 0$

=color(blue)((x+4)(x-7)

Now, we can equate the two factors with zero and find the solutions:

• x+4 =0, color(blue)(x=-4
• x-7 =0, color(blue)(x=7
Jun 28, 2015