Question

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

{1.72, –0.58}
{-7, 8}
{–1.14, –1.00}
{–1.00, 1.14}

Answer 1

Can you use the quadratic formula?

Answer 2

yea kind of I get stuck with when to use +/-

Answer 3

x=-b +/- sqrt b^2-4ac/2a right?

Answer 4

Yes.

You use both of them.\[\dfrac{-b \pm \sqrt{b^2 - 4ac}}{2a}\]Means that the roots are \[\dfrac{-b+ \sqrt{b^2 - 4ac}}{2a}\]and\[\dfrac{-b - \sqrt{b^2 - 4ac}}{2a}\]

Answer 5

so -8 + sqrt 260/ -14 and -8 - sqrt 260/ -14 and i get lost from here