655)
a)(5x³-3x²-7)+(4+3x²-5x³)=5x³-3x²-7+4+3x²-5x³=-3
b)(z²-3z+2)+(4z+8)+(3z²-5)=z²-3z+2+4z+8+3z²-5=4z²+z+5
c)(3t³-4t²+7t)+(2t²-6t+7)=3t³-4t²+7t+2t²-6t+7=3t³-2t²+t+7
d)(2a²+5a)+(-a²+a)+(a²-3a-5)=2a²+5a-a²+a+a²-3a-5=2a²+3a-5
657)
a)(10a-2b+5c)-(-5a+20b-c)=10a-2b+5c+5a-20b+c=15a+6c-22b
b)(16m-11n-7nm)-(6nm-10n+16m)=16m-11n-7mn-6mn+10n-16m=-n-13mn=-n(1+13m)
c)(c²+3cd-d²)-(4cd+5d²-6c²)=c²+3cd-d²-4cd-5d²+6c²=7c²-cd-6d²
d)(3b³-2ab+a³)-(2ab+3b³)=3b³-2ab+a³-2ab-3b³=a³-4ab=a(a-4b)