1) -а ^ 2-в^ 2+2а^ 2-в^ 2 = a^2 - 2b^2

2) 3х^ 3-2у-5х^ 3-2+2у-7 = - 2x^3 -9

3) mn-7mn^ 2-mn-7mn^ 2 = - 14mn^2

4) 5xz^ 2-4x^ 2z+xz-5xz^ 2=  -4x^ 2z+xz

5) 1.4z^ 3-0.1z^ 2-0.4z^ 3+1 = z^3 -0.1 z^2 +1

6) a^ 2+a+1\4a^ 2-a= 5a^2/4

7) 1\3x+2\3x^ 3-x-2\3x^ 3+3 = - 2/3 x + 3

8) 2\5b^ 2+b-3\5b^ 2+1\4b = - b^2/5 + 5b/4