How do you find all the zeros of f(x) = x^4 + 2x^3 + 22x^2 + 50x - 75f(x)=x4+2x3+22x2+50x75?

1 Answer
Feb 26, 2016

Zeros of x^4+2x^3+22x^2+50x-75x4+2x3+22x2+50x75 are -33 and 11

Explanation:

To find all the zeros of P(X)=x^4+2x^3+22x^2+50x-75P(X)=x4+2x3+22x2+50x75, first find a factor of the independent term 7575 such as

{1, -1, 3, -3, 5, -5, 15, -15, ....} for which P(x)=0.

It is apparent that for x=1 as well as for x=-3, P(x)=0. Hence 1 and -3 are two zeros of x^4−4x^3−35x^2+6x+144

Hence, (x-1)(x+3) or x^2+2x-3 divides P(x). Dividing latter by former, we get

(x^4+2x^3+22x^2+50x-75)/(x^2+2x-3) = x^2+25

As the RHS cannot be factorized in real factors there are no further zeros.

Hence zeros of x^4+2x^3+22x^2+50x-75 are -3 and 1