câu1,(2x-1).(3x+2).(3-x) câu2,(x+3).(x mũ 2+3x-5)

Câu 1: (2x-1).(3x+2).(3-x)

= (2x.3x)+(2x.2)+(-1.3x)+(-1.2).(3-x)

=5x mũ2+4x-3x-2.(3-x)

=5x mũ2+(x-2).(3-x)

=5x mũ2+(x.3)+(x.-x)+(-2.3)+(-2.-x)

=5x mũ2+3x-x mũ2-5x+2x

=4x mũ2-2x+2x

Câu 2:(x-3).(x mũ2+3x-5)

=(x.x mũ2)+(x.3x)+(x.-5)+(3.x mũ2)+(3.3x)+(3.-5)

=x mũ3+3x mũ2-5x+3x mũ2+9x-15

=x mũ3+6x mũ2+4x-15