college algebra, Please help!!
posted by ladybug on .
find a bound on the real zeros of the polynomial.
f(x)=x^4+2x^38x7
every real zero of f lies between ? and ?
*pleasae show all work*

using synthetic division, dividing by xa, take a look at the signs of the numbers in the quotient.
x0: 1 2 0 8 7
x1: 1 3 3 5 12
x2: 1 4 8 8 9
all signs are positive, so all real roots are all less than 2.
Similarly, for negative values,
x+1: 1 1 1 7 0
x+2: 1 0 0 8 9
x+3: 1 1 3 17 44
signs alternate, so all real roots are greater than 3