# How do you solve the equation x^2+1.4x=1.2 by completing the square?

May 19, 2017

$x = 0.6$ or $x = - 2$

#### Explanation:

Divide the coefficient of the $x$ term by $2$ and square it.

$\frac{1.4}{2} = 0.7$

${\left(0.7\right)}^{2} = 0.49$

Now add it to both sides of the equation

${x}^{2} + 1.4 x + 0.49 = 1.2 + 0.49$

This becomes

${\left({x}^{2} + 0.7\right)}^{2} = 1.69$

Take the square root of both sides

$\sqrt{{\left(x + 0.7\right)}^{2}} = \pm \sqrt{1.69}$

$x + 0.7 = \pm 1.3$

$x = \pm 1.3 - 0.7$

$x = 1.3 - 0.7 = 0.6$

$x = - 1.3 - 0.7 = - 2$