SOLUTION: Select the approximate values of x that are solutions to f(x) = 0, where f(x) = -7x2 + 2x + 8. {–0.94, 1.22} {-7, 2} {–0.29, –1.14} {–0.88, 0.25}

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons  -> Quadratic Equation Lesson -> SOLUTION: Select the approximate values of x that are solutions to f(x) = 0, where f(x) = -7x2 + 2x + 8. {–0.94, 1.22} {-7, 2} {–0.29, –1.14} {–0.88, 0.25}      Log On


   

Question 945953: Select the approximate values of x that are solutions to f(x) = 0, where
f(x) = -7x2 + 2x + 8.

{–0.94, 1.22}

{-7, 2}

{–0.29, –1.14}

{–0.88, 0.25}
Answer by MathLover1(20849) About Me  (Show Source):
You can put this solution on YOUR website!

f%28x%29+=+-7x%5E2+%2B+2x+%2B+8

0=+-7x%5E2+%2B+2x+%2B+8....use quadratic formula

x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+

x+=+%28-2+%2B-+sqrt%28+2%5E2-4%2A%28-7%29%2A8+%29%29%2F%282%2A%28-7%29%29+

x+=+%28-2+%2B-+sqrt%284%2B224%29%29%2F%28-14%29+

x+=+%28-2+%2B-+sqrt%28228%29%29%2F%28-14%29+
x+=+%28-2+%2B-+15.0996688705415%29%2F%28-14%29+
solutions:
x+=+%28-2+%2B+15.0996688705415%29%2F%28-14%29+

x+=+%28+13.0996688705415%29%2F%28-14%29+

x+=+-0.9356906336101071+

highlight%28x+=+-0.94+%29

or
x+=+%28-2+-+15.0996688705415%29%2F%28-14%29+

x+=+%28+-17.0996688705415%29%2F%28-14%29+

x+=+1.221404919324393+

highlight%28x+=+1.22%29

so, answer is: {–0.94, 1.22}