How do you solve $7 x^{2} + 8 x + 5 = 0$ $7x^2 + 8x + 5 = 0$ using the quadratic formula?

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How do you solve $7 x^{2} + 8 x + 5 = 0$ $7x^2 + 8x + 5 = 0$ using the quadratic formula?

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Answer 1 · 2016-03-08T11:02:10

$x = \frac{- 8 \pm 2 \sqrt{- 19}}{14}$ $x= (-8+-2sqrt(-19))/14$

Explanation:

The quadratic formula states that the solutions to a quadratic of the form $a x^{2} + b x + c = 0$ $ax^2 +bx+c = 0$ are given by

$x = \frac{- b \pm \sqrt{b^{2} - 4 a c}}{2 a}$ $x =( -b+-sqrt(b^2-4ac))/(2a)$

So in this case

$x = \frac{- 8 \pm \sqrt{8^{2} - 4 \cdot 7 \cdot 5}}{2 \cdot 7}$ $x = (-8+-sqrt(8^2-4*7*5))/(2*7)$

$= \frac{- 8 \pm \sqrt{64 - 140}}{14} = \frac{- 8 \pm \sqrt{- 76}}{14} = \frac{- 8 \pm 2 \sqrt{- 19}}{14}$ $=(-8+-sqrt(64-140))/14 = (-8+-sqrt(-76))/14 = (-8+-2sqrt(-19))/14$

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How do you solve $7 x^{2} + 8 x + 5 = 0$ $7x^2 + 8x + 5 = 0$ using the quadratic formula?

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