當a=1/3,b=0.2時,求a³;-b³;/a²;+ab+b²;的值

當a=1/3,b=0.2時,求a³;-b³;/a²;+ab+b²;的值

∵a³;-b³;=(a-b)(a²;+ab+b²;)當a=1/3,b=0.2時,∴(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