Question 28808
find the sum 3m-4n-7,and 7n+2
Sum of 3m-4n-7,and 7n+2
=(3m-4n-7)+[(0)m+7n+2]
=[3m+(0)m]+[(-4n)+7n]+[(-7)+2] (grouping like terms which is nothing but applying additive commutativity and associativity)
=3m+3n-5

find the sum -7xy+15xy+(-11xy)+(-xy)+2xy
The sum -7xy+15xy+(-11xy)+(-xy)+2xy
=[(-7)+15+(-11)+(-1)+2](xy)
=[-7+15-11-1+2](xy)
=[(-7-11-1)+(15+2)](xy)
=(-19+17)(xy)
=-2xy
Note: Since every term is (xy) term you may add orally!