Question

先化简在求值（a-b分之a - a²-2ab+b²分之a²)除以(a+b分之a - a

Answer 1

a/(a-b)- a^2/(a^2-2ab+b^2)÷[(a/a+b -a^2/(a^2-b^2)]+1

=a(a-b)/(a-b)^2-a^2/(a-b)^2÷[a(a-b)/(a^2-b)-a^2/(a^2-b^2)]+1

=-ab/(a-b)^2÷[-b/(a^2-b^2)]+1

=-a(a+b)/(a-b)+1

将 a=2/3 b=-3代入

有 -2/3(2/3-3)/(2/3+3)+1

=-2/3*(-7/3)*3/11+1

=14/33+1

=47/33