Question

Cho m và n là các số nguyên dương

A=2+4+6+...+2m/m

B=2+4+6+...+2n//n

Biết A<b, hãy so sánh m và n

Answer 1

\(A=\frac{\left(2+2m\right).m}{2m}=\frac{2\left(1+m\right).m}{2m}=1+m\)

\(B=\frac{\left(2+2n\right).n}{2n}=\frac{2\left(1+n\right).n}{2n}=1+n\)

do A<B=>1+m<1+n=>m<n

Answer 2

Ta có: A=\(\frac{\frac{\left(2m+2\right)\left[\frac{2m-2}{2}+1\right]}{2}}{m}=\frac{\frac{2\left(m+1\right)m}{2}}{m}=\frac{\left(m+1\right)}{m}\)=m+1

B= \(\frac{\frac{\left(2n+2\right)\left[\frac{2n-2}{2}+1\right]}{2}}{n}=\frac{\frac{2\left(n+1\right)n}{2}}{n}=\frac{\left(n+1\right)n}{n}\)=n+1

Mà A<B

=>m+1<n+1

=>m<n