Find all rational zeros of the function. Then (if necessary) use the depressed equation to find all roots of the equation f(x)=0

Question

f(x)= 5x^4-11x^3-33x^2+77x-14

Answer 1

trying x = ±1, ±2, ± 7, ±1/5, ±2/5, ±7/5
I found f(2) = 0
and f(x) = (x-2)(5x^3 - x^2 - 35x + 7) = (x-2)g(x)
x = ±7 didn't work in the first, so it certainly will not work in this one
so try x = 1/5 in the cubic factor
g(1/5) = 5(1/125) - 1/25 - 35(1/5) + 7 = 0

so we have
f(x) = (x-2)(5x-1)(x^2 - 7) after a division

roots are
x = 2, 1/5, ± √7