Bài 56 trang 18 SBT toán 7 tập 1

So sánh \({99^{20}}\) và \({9999^{10}}\).

Lời giải

Ta có:

\(\eqalign{
& {99^{20}} = {\left( {{{99}^2}} \right)^{10}} = {9801^{10}} \cr 
& 9801 < 9999 \Rightarrow {9801^{10}} < {9999^{10}} \cr} \)

Vậy \({99^{20}} < {9999^{10}}\)


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