合并下列格式中的同类项：(1)1/2xy-1/4x+xy(2)3a^2b-4ab+2a-1-3a^2b-4ab-5-a^2b(3)3(a+b)+(a+b)-5(a+b)那（m+n)^2-3(m-n)^2+5(m-n)^2

Question

合并下列格式中的同类项：(1)1/2xy-1/4x+xy (2)3a^2b-4ab+2a-1-3a^2b-4ab-5-a^2b (3)3(a+b)+(a+b)-5(a+b)
那（m+n)^2-3(m-n)^2+5(m-n)^2

Answer 1

(1)1/2xy-1/4x+xy
=(1/2-1/4+1)xy
=5/4xy
(2)3a^2b-4ab+2a-1-3a^2b-4ab-5-a^2b
=3a^2b-3a^2b-a^2b-4ab-4ab+2a-1-5
=(3-3-1)a^2b-(4+4)ab+2a-6
=-a^2b-8ab+2a-6
(3)3(a+b)+(a+b)-5(a+b)
=(3+1-5)(a+b)
=-(a+b)