Problem
2) Let \( P(x)=x^{4}+5 x^{3}+4 x^{2}-3 x+9 \). a) Compute \( P(-3) \). b) Decompose P into irreducible factors.
Solution
Step 1 ：P(-3) = (-3)^{4}+5(-3)^{3}+4(-3)^{2}-3(-3)+9
Step 2 ：P(-3) = 81-135+36+9+9
Step 3 ：P(-3) = 0
Step 4 ：P(x) = (x+3)(x^3+2x^2-x+3)
