当a=1/3,b=0.2时,求a³-b³/a²+ab+b²的值

当a=1/3,b=0.2时,求a³-b³/a²+ab+b²的值
当a=1/3,b=0.2时,求a³-b³/a²+ab+b²的值

当a=1/3,b=0.2时,求a³-b³/a²+ab+b²的值
∵a³-b³=（a-b)(a²+ab+b²)
当a=1/3,b=0.2时,
∴(a³-b³)/(a²+ab+b²)
=（a-b)(a²+ab+b²)/(a²+ab+b²)
=a-b
=1/3-0.2
=1/3-1/5
=2/15

a³-b³/a²+ab+b²=(a-b)*(a²+ab+b²)/(a²+ab+b²)=a-b=2/15

当a=1/3,b=0.2时,求a³-b³/a²+ab+b²=(a-b)(a²+ab+b²)/(a²+ab+b²)=a-b=1/3-0.2=2/15