số hạng là:

(21,25-3,25):1,50+1=13(số hạng)

tổng là:

(3,25+21,25).13:2=159,25

38.500  x 3,5 : 5 =26950 nha

HT~~~(^-^)

Mình nhìn nhầm dấu chấm!
Trả lời lại :

= 26 950

~HT~

Trả lời : 

= 26,95

~HT~

#sad

\(a,17^{20}=\left(17^4\right)^5=83521^5;31^{15}=\left(31^3\right)^5=29791^5\\ Vì:83521^5>29791^5\Rightarrow17^{20}>31^{15}\)

\(b,199^{20}=\left(199^5\right)^4=312079600999^4\\ 100^{24}=\left(100^6\right)^4=1000000000000^4\\ Vì:312079600999^4< 1000000000000^4\Rightarrow199^{20}< 100^{24}\\ c,31^{11}< 32^{11}\\ Mà:32^{11}=\left(2^5\right)^{11}=2^{55}\Rightarrow31^{11}< 2^{55}\\ 17^{14}>16^{14}\\ Mà:16^{14}=\left(2^4\right)^{14}=2^{56}\Rightarrow17^{14}>2^{56}\\ \Rightarrow31^{11}< 2^{55}< 2^{55}< 17^{14}\\ Vậy:31^{11}< 17^{14}\)

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