Question

So sánh:

A=2016^90+2016^91

B=2017^91

Answer 1

Ta có :

A=2016^90 + 2016^91

  = 2016^90( 2016+1)

  = 2016^ 90x2017

B=2017^91

  = 2017^90x2017

Vì 2017=2017 

mà 2016^90<2017^90

=> B>A

Vậy B>A

Answer 2

\(A=2016^{90}+2016^{91}\)

\(=2016^{90}+2016^{90}.2016\)

\(=2016^{90}\left(1+2016\right)\)

\(=2016^{90}.2017\)

\(B=2017^{91}=2017^{90}.2017\)

Suy ra :  A<B