Step 1 Concept used: For a quadratic equation of the form x2+bx+c=0 the solutions are x1,2=−b±b2−4c2 Step 2 Compare x2+8x+7=0 with x2+bx+c=0 Here b=8, c=7 x1,2=−b±b2−4c2 ⇒x=−(8)+(8)2−4(7)2 x=−(8)−(8)2−4(7)2 ⇒x=−8+64−282 x=−8−64−282 ⇒x=−8+362 x=−8−362 ⇒x=−8+62 x=−8−62 ⇒x=−22 x=−142 ⇒x=−1 x=−7 Solution of the x2+8x+7=0 are x=−1, x=−7

Expert Answer to "To solve x2=8x+7=0"

High School
Algebra
Algebra I
Algebra foundations

Ann Tice

Answered question

2021-11-13

To solve

x^{2} = 8 x + 7 = 0

Answer & Explanation

Steacensen69

Beginner2021-11-14Added 15 answers

Step 1
Concept used:
For a quadratic equation of the form

x^{2} + b x + c = 0

the solutions are

x_{1, 2} = \frac{- b \pm \sqrt{b^{2} - 4 c}}{2}

Step 2
Compare

x^{2} + 8 x + 7 = 0

with

x^{2} + b x + c = 0

Here

b = 8, c = 7

x_{1, 2} = \frac{- b \pm \sqrt{b^{2} - 4 c}}{2}

\Rightarrow x = \frac{- (8) + \sqrt{{(8)}^{2} - 4 (7)}}{2}

x = \frac{- (8) - \sqrt{{(8)}^{2} - 4 (7)}}{2}

\Rightarrow x = \frac{- 8 + \sqrt{64 - 28}}{2}

x = \frac{- 8 - \sqrt{64 - 28}}{2}

\Rightarrow x = \frac{- 8 + \sqrt{36}}{2}

x = \frac{- 8 - \sqrt{36}}{2}

\Rightarrow x = \frac{- 8 + 6}{2}

x = \frac{- 8 - 6}{2}

\Rightarrow x = \frac{- 2}{2}

x = \frac{- 14}{2}

\Rightarrow x = - 1

x = - 7

Solution of the

x^{2} + 8 x + 7 = 0

are

x = - 1, x = - 7

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