Exercises: Terms with Square Roots

When solving quadratic equations, one obtains expressions with square roots, like the following two. Simplify them.

$x_{1 / 2} = \frac{- 5 \pm \sqrt{5^{2} + 4 \cdot \sqrt{7} \cdot 2 \sqrt{7}}}{2 \sqrt{7}}$

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$x_{1 / 2}$	$=$	$\frac{- 5 \pm \sqrt{5^{2} + 4 \cdot \sqrt{7} \cdot 2 \sqrt{7}}}{2 \sqrt{7}}$
	↓	Conclude everything under the root.
$x_{1 / 2}$	$=$	$\frac{- 5 \pm \sqrt{81}}{2 \sqrt{7}} = \frac{- 5 \pm 9}{2 \sqrt{7}}$
$x_{1}$	$=$	$\frac{- 5 + 9}{2 \sqrt{7}} = \frac{4}{2 \sqrt{7}}$
	↓	Shorten by 2
$x_{1}$	$=$	$\frac{2}{\sqrt{7}}$
	↓	Expand by $\sqrt{7}$ .
$x_{1}$	$=$	$\frac{2 \cdot \sqrt{7}}{\sqrt{7} \cdot \sqrt{7}} = \frac{2 \sqrt{7}}{7}$
$x_{2}$	$=$	$\frac{- 5 - 9}{2 \sqrt{7}} = \frac{- 14}{2 \sqrt{7}}$
	↓	Expand by $\sqrt{7}$ .
$x_{2}$	$=$	$\frac{- 14 \sqrt{7}}{2 \sqrt{7} \sqrt{7}} = \frac{- 14 \sqrt{7}}{2 \cdot 7} = \frac{- 14 \sqrt{7}}{14}$
	↓	Shorten by 14.
$x_{2}$	$=$	$- \sqrt{7}$

$x_{1 / 2}$	$=$	$\frac{- 14 \pm \sqrt{14^{2} - 4 \cdot 8}}{2}$
	↓	Conclude everything under the root.
	$=$	$\frac{- 14 \pm \sqrt{164}}{2}$
	↓	Pull 2 out of the root.
	$=$	$\frac{- 14 \pm \sqrt{4 \cdot 41}}{2} = \frac{- 14 \pm 2 \sqrt{41}}{2}$
	↓	Shorten the fractions.
	$=$	$- 7 \pm \sqrt{41}$