Find the general solution to y" + 2y' + 17y = 0

Y=4x^2+x-1 solve using quadratic formula

Which of the following represents the zeros of f(x) = 6x3 − 31x2 + 4x + 5? −5, one third , one half 5, − one third , one half 5, one third , − one half 5, one third , one half

Can someone me with #s 8, 9, and 11. with just one of the three also works. prove using only trig identities.