4x^3-31x+15=?

问题描述:

4x^3-31x+15=?
分解因式

4x^3-31x+15
=4x^3-x-30x+15
=x(4x^2-1)-15(2x-1)
=x(2x+1)(2x-1)-15(2x-1)
=(2x^2+x-15)(2x-1)
=(2x-5)(x+3)(2x-1)