In each of the following, use factor theorem to find whether polynomial g(x) is a factor of polynomial f(x) or, not:
f(x) = 3x4+17x3+9x2-7x-10, g(x) = x+5
We have,
f(x) = 3x4+17x3+9x2-7x-10 and g(x) = x+5
In order to find whether the polynomials g (x) = x – (-5) is a factor of f (x) or not, it is sufficient to show that f (-5) = 0
Now,
f(x) = 3x4+17x3+9x2-7x-10
f (-5) = 3 (-5)4 + 17 (-5)3 + 9 (-5)2 – 7 (-5) – 10
= 3 * 625 + 17 * (-125) + 9 * 25 + 35 – 10
= 1875 – 2125 + 225 + 35 – 10
= 0
Hence, g (x) is a factor of f (x).