Select the approximate values of x that are solutions to f(x) = 0, where
f(x) = -9x2 + 3x + 5.
which one is correct:
{0.93, –0.60}
{-9, 3}
{–0.33, –0.56}
{–1.80, 0.60}
f(x) = -9(x^2-1/3) + 5
= -9(x^2 - 1/3 + 1/36) + 5 + 1/4
= -9(x - 1/6)^2 + 21/4
f(x) = 0 when
9(x - 1/6)^2 = 21/4
x = (1±√21)/6
. . .