Toán So sánh : A=-7/10 mũ 2005 + -15/10 mũ 2006 B =-15/10 mũ 2005 + -7/10 mũ 2006 13/09/2021 By Jasmine So sánh : A=-7/10 mũ 2005 + -15/10 mũ 2006 B =-15/10 mũ 2005 + -7/10 mũ 2006
`A=(-7)/10^{2005}+(-15)/10^{2006}` `A=(-7)/10^{2005}+(-7)/10^2006+(-8)/10^2006` `B=(-15)/10^2005+(-7)/10^2006` `B=(-8)/10^2005+(-7)/10^2005+(-7)/10^2006` Ta thấy `(-8)/10^2005>(-8)/10^2006` nên `(-7)/10^{2005}+(-7)/10^2006+(-8)/10^2006<(-8)/10^2005+(-7)/10^2005+(-7)/10^2006` Vậy `A<B`. Trả lời
`A=(-7)/10^{2005}+(-15)/10^{2006}`
`A=(-7)/10^{2005}+(-7)/10^2006+(-8)/10^2006`
`B=(-15)/10^2005+(-7)/10^2006`
`B=(-8)/10^2005+(-7)/10^2005+(-7)/10^2006`
Ta thấy `(-8)/10^2005>(-8)/10^2006` nên
`(-7)/10^{2005}+(-7)/10^2006+(-8)/10^2006<(-8)/10^2005+(-7)/10^2005+(-7)/10^2006`
Vậy `A<B`.