Question

因式分解:x^4+8x^3+15x^2-4x-20(过程)

Answer 1

x^4+8x^3+15x^2-4x-20=x^2(x^+8x+15)-4(x+5)=x^2(x+3)(x+5)-4(x+5)=(x-5)[x^2(x-3)-4]=(x-5)(x^3-3x^2-4)

x----- +3

x----- +5

x^2+8x+15