Solve Using the Quadratic Formula y^2-6y+7=0

$y^{2} - 6 y + 7 = 0$

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 $a = 1$ , $b = - 6$ , and $c = 7$ into the quadratic formula and solve for $y$ .

$\frac{6 \pm \sqrt{{(- 6)}^{2} - 4 \cdot (1 \cdot 7)}}{2 \cdot 1}$

Step 3

Simplify.

Simplify the numerator.

Raise $- 6$ to the power of $2$ .

$y = \frac{6 \pm \sqrt{36 - 4 \cdot 1 \cdot 7}}{2 \cdot 1}$

Multiply $- 4 \cdot 1 \cdot 7$ .

Multiply $- 4$ by $1$ .

$y = \frac{6 \pm \sqrt{36 - 4 \cdot 7}}{2 \cdot 1}$

Multiply $- 4$ by $7$ .

$y = \frac{6 \pm \sqrt{36 - 28}}{2 \cdot 1}$

Subtract $28$ from $36$ .

$y = \frac{6 \pm \sqrt{8}}{2 \cdot 1}$

Rewrite $8$ as $2^{2} \cdot 2$ .

Factor $4$ out of $8$ .

$y = \frac{6 \pm \sqrt{4 (2)}}{2 \cdot 1}$

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

$y = \frac{6 \pm \sqrt{2^{2} \cdot 2}}{2 \cdot 1}$

Pull terms out from under the radical.

$y = \frac{6 \pm 2 \sqrt{2}}{2 \cdot 1}$

Multiply $2$ by $1$ .

$y = \frac{6 \pm 2 \sqrt{2}}{2}$

Simplify $\frac{6 \pm 2 \sqrt{2}}{2}$ .

$y = 3 \pm \sqrt{2}$

Step 4

The result can be shown in multiple forms.

Exact Form:

$y = 3 \pm \sqrt{2}$

Decimal Form:

$y = 4.41421356 \dots, 1.58578643 \dots$