Solve Using the Quadratic Formula 5x^2-7=0

$5 x^{2} - 7 = 0$

Step 1

Use the quadratic formula to find the solutions.

$\frac{- b \pm \sqrt{b^{2} - 4 (a c)}}{2 a}$

Step 2

Substitute the values $a = 5$ , $b = 0$ , and $c = - 7$ into the quadratic formula and solve for $x$ .

$\frac{0 \pm \sqrt{0^{2} - 4 \cdot (5 \cdot - 7)}}{2 \cdot 5}$

Step 3

Simplify.

Simplify the numerator.

Raising $0$ to any positive power yields $0$ .

$x = \frac{0 \pm \sqrt{0 - 4 \cdot 5 \cdot - 7}}{2 \cdot 5}$

Multiply $- 4 \cdot 5 \cdot - 7$ .

Multiply $- 4$ by $5$ .

$x = \frac{0 \pm \sqrt{0 - 20 \cdot - 7}}{2 \cdot 5}$

Multiply $- 20$ by $- 7$ .

$x = \frac{0 \pm \sqrt{0 + 140}}{2 \cdot 5}$

Add $0$ and $140$ .

$x = \frac{0 \pm \sqrt{140}}{2 \cdot 5}$

Rewrite $140$ as $2^{2} \cdot 35$ .

Factor $4$ out of $140$ .

$x = \frac{0 \pm \sqrt{4 (35)}}{2 \cdot 5}$

Rewrite $4$ as $2^{2}$ .

$x = \frac{0 \pm \sqrt{2^{2} \cdot 35}}{2 \cdot 5}$

Pull terms out from under the radical.

$x = \frac{0 \pm 2 \sqrt{35}}{2 \cdot 5}$

Multiply $2$ by $5$ .

$x = \frac{0 \pm 2 \sqrt{35}}{10}$

Simplify $\frac{0 \pm 2 \sqrt{35}}{10}$ .

$x = \frac{\pm \sqrt{35}}{5}$

Step 4

The result can be shown in multiple forms.

Exact Form:

$x = \frac{\pm \sqrt{35}}{5}$

Decimal Form:

$x = 1.18321595 \dots, - 1.18321595 \dots$