Question 974183
x4 -7x + 8
potential rational roots are factors of 8/factors of 1, and +/-.  You divide the constant by the leading coefficient.

+/-8; +/- 4 ; +/-2; +/-1

In this instance there are no rational roots.



{{{graph(300,300,-10,10,-10,10,x^4-7x+8)}}}