Question

a-3/a-2,-(a-2)(3-a)/a+1

通分

Answer 1

-(a-2)(3-a)/(a+1)
=(a-2)(a-3)/(a+1)
所以最简公分母是(a-2)(a-3)

所以(a-3)/(a-2)
=(a-2)(a-3)/(a-2)平方

-(a-2)(3-a)/(a+1)
=(a-2)(a-3)/(a+1)

Answer 2

bn/b(n-1)=√[a(n+1)a(n+2)]/√[ana(n+1)]=q
平方
a(n+2)=an*q^2

cn/c(n-1)
=[a(2n-1)+2a(2n)]/[a(2n-3)+2a(2n-2)]
a(2n-1)=a(2n-3)*q^2
a(2n)=a(2n-2)*q^2
所以cn/c(n-1)=q^2
所以cn是等比数列