Question

因式分解：x^3+3x-4,4x^2+2x-y-y^2

Answer 1

x^3+3x-4

=x^3 + (x^2 - x^2) + (4 x - x) - 4

=x^3 + x^2 + 4 x - x^2 - x - 4

= (x^2 + x + 4) x - (x^2 + x + 4)

= (x^2 + x + 4)(x -1)

4 x^2 + 2 x - y - y^2

=4 x^2 - y^2 +(2 x - y)

=(2 x + y)(2 x - y)+(2 x - y)

=(2 x + y + 1)(2 x - y)