How do you solve $x^{2} + 8 x = - 2$ $x^2+8x=-2$ using the quadratic formula?

Question

How do you solve $x^{2} + 8 x = - 2$ $x^2+8x=-2$ using the quadratic formula?

2 Answers

Impact of this question

2900 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2018-04-16T21:08:39

$x = - 4 \pm \sqrt{14}$ $x=-4+-sqrt14$

Explanation:

First add $2$ $2$ to each side so that the equation is in standard form: $y = a x^{2} + b x + c$ $y=ax^2+bx+c$ .

$x^{2} + 8 x + 2 = 0$ $x^2+8x+2=0$

The quadratic formula is $\frac{- b \pm \sqrt{b^{2} - 4 a c}}{2 a}$ $(-b+-sqrt(b^2-4ac))/(2a)$ .

Here, $a$ $a$ is $1$ $1$ , $b$ $b$ is $8$ $8$ , and $c$ $c$ is $2$ $2$ . Let's plug these numbers into the quadratic formula.

$\frac{- 8 \pm \sqrt{8^{2} - 4 \cdot 1 \cdot 2}}{2 \cdot 1}$ $(-8+-sqrt(8^2-4*1*2))/(2*1)$

$\frac{- 8 \pm \sqrt{64 - 8}}{2}$ $(-8+-sqrt(64-8))/2$

$\frac{- 8 \pm \sqrt{56}}{2}$ $(-8+-sqrt56)/2$

$\frac{- 8 \pm 2 \sqrt{14}}{2}$ $(-8+-2sqrt14)/2$

$- 4 \pm \sqrt{14}$ $-4+-sqrt14$

$x = - 4 \pm \sqrt{14}$ $x=-4+-sqrt14$

Answer 2 · 2018-04-16T21:11:42

$x = - .258, - 7.74$ $x=-.258, -7.74$ Those are averaged btw

Explanation:

first move the two over to the right side
$x^{2} + 8 x + 2 = 0$ $x^2 +8x +2=0$
Now plug into quadratic formula knowing that a quadratic equation is just $a x^{2} + b x + c = 0$ $ax^2 +bx +c=0$ and the quadratic formula is $x = \frac{- b \pm (\sqrt b^{2} - 4 a c)}{2 a}$ $x=(-b+-(√b^2-4ac))/(2a)$
$x = \frac{- (8) \pm (\sqrt {(8)}^{2} - 4 (1) (2))}{2 (1)}$ $x=(-(8)+-(√(8)^2-4(1)(2)))/(2(1))$
$x = \frac{- 8 \pm (\sqrt 64 - 8)}{2}$ $x=(-8+-(√64-8))/(2)$
$x = \frac{- 8 + (\sqrt 56)}{2}$ $x=(-8+(√56))/2$ or $x = \frac{- 8 - (\sqrt 56)}{2}$ $x=(-8-(√56))/2$
Which means $x = - .258, - 7.74$ $x=-.258, -7.74$

Science

Math

Humanities

... and beyond

How do you solve $x^{2} + 8 x = - 2$ $x^2+8x=-2$ using the quadratic formula?

2 Answers

Explanation:

Explanation:

Related questions

Impact of this question

Science

Math

Humanities

... and beyond

How do you solve x2+8x=−2x^2+8x=-2 using the quadratic formula?

2 Answers

Explanation:

Explanation:

Related questions

Impact of this question

How do you solve $x^{2} + 8 x = - 2$ $x^2+8x=-2$ using the quadratic formula?