Найдите a+b, a-b, b*a, a*b, зная,что; 1)a=5m, b=-4m-n, 2)a=2x-3y, b=2x-4y

1)A=5m, B=-4m-n.


A+B=5m+(-4m-n)=5m-4m-n=m-n
A-B=5m-(-4m-n)=5m+4m+n=9m+n
B*A=(-4m-n)*5m=-20m²-5mn
A*B=5m*(-4m-n)=-20m²-5mn

 2)A=2x-3y, B=2x-4y.


A+B=(2x-3y)+(2x-4y)=2x-3y+2x-4y=4x-7y
A-B=(2x-3y)-(2x-4y)=2x-3y-2x+4y=y
B*A=(2x-4y)*(2x-3y)=4x²-8yx-6xy+12y²=4x²-14xy+12y²
A*B=(2x-3y)*(2x-4y)=4x²-6yx-8xy+12y²=4x²-14xy+12y²

1)A+B
5m+(-4m-n)=5m+4m-n=9m-n
2)A-B
5m-(-4m-n)=5m+4m-n=9m-n
3)B*A
2x-4y*2x-3y=4x-y
4)A*B
2x-3y*2x-4y=4x-7y