3x³-2x·x²
=3x^3-2x^3
=x^3
a·a²·a³+2a的四次方乘以a²-3a³·a³
=a^6+2a^4*a^2-3a^6
=a^6+2a^6-3a^6
=0
（a-b）²·（a-b）³+（a-b）的四次方乘以（-a-b）
=(a-b)^5+(a-b)^4*(-a+b)
=(a-b)^5-(a-b)^5
=0
（a-b-c）³·（b+c-a）²
=（a-b-c）^3·（a-b-c）^2
=(a-b-c)^5
a³·a的五次方减去（a³）的五次方
=a^5*a^3-(a^3)^5
=a^8-a^15
[（a-b）²]³-[（b-a）³]²
=(a-b)^6-(a-b)^6
=0
2x·x³+（x²）²
=2x^4+x^4
=3x^4