Thực hiện phép tính: a) (3zyz - 3x^2 + 5xy - 1) - (5x^2 + xyz - 5xy + 3 - y);

a) 3xyz−3x2+5xy−1−5x2+xyz−5xy+3−y

=3xyz−3x2+5xy−1−5x2−xyz+5xy−3+y

=3xyz−xyz+−3x2−5x2+5xy+5xy+y+−1−3

=2xyz−8x2+10xy+y−4.

b) 3x3−x2y+2xy+3+x2y−2xy−2

=3x3−x2y+2xy+3+x2y−2xy−2

=(−x2y)+(x2y)+(2xy−2xy)+3x3+(3−2)

=3x3+1.

 

c) (2xy3−4y−8x)⋅12y

=2xy3.12y+(−4y).12y+(−8x).12y

=xy4−2y2−4xy.

 

d) x8y8+2x5y5+7x3y3:−x2y2

=x8y8:−x2y2+2x5y5:−x2y2+7x3y3:−x2y2

=−x6y6−2x3y3−7xy.