# How do you solve x(2x + 7) = 4?

Apr 23, 2016

$x = - 4 \mathmr{and} x = \frac{1}{2}$

#### Explanation:

$\implies 2 {x}^{2} + 7 x - 4 = 0$
$\implies 2 {x}^{2} + 8 x - x - 4 = 0$
$\implies 2 x \left(x + 4\right) - 1 \left(x + 4\right) = 0$
$\implies \left(x + 4\right) \left(2 x - 1\right) = 0$
$x = - 4 \mathmr{and} x = \frac{1}{2}$

Apr 23, 2016

x = -4
OR
x = -0.5

#### Explanation:

x(2x + 7) = 4
First multiply out the brackets and bring the 4 to the left hand side
2x^2 + 7x - 4 = 0
Then plug the above equation into the quadratic formula where
a = 2 b=7 and c= -4
(-7 ± sqrt(49 - (4 * 2 * -4))/ 4)

This will give you two answers using the +/- before the square root for 2 different answers.