Ta có: \(\frac{\frac{3}{7}-\frac{3}{17}+\frac{3}{171}-\frac{3}{1717}}{\frac{9}{7}-\frac{9}{17}+\frac{9}{171}-\frac{9}{1717}}\)= \(\frac{3.\left(\frac{1}{7}-\frac{1}{17}+\frac{1}{171}-\frac{1}{1717}\right)}{9.\left(\frac{1}{7}-\frac{1}{17}+\frac{1}{171}-\frac{1}{1717}\right)}\)=\(\frac{3}{9}=\frac{1}{3}\)

a)Ta có:

1 - 219/220 = 1/220

1 - 215/216 = 1/216

Vì 1/220 < 1/216 suy ra 219/220 > 215/216

Vậy 219/220 > 215/216

a) Ta có: \(\frac{219}{220}+\frac{1}{220}=1\); \(\frac{215}{216}+\frac{1}{216}=1\)

Mà \(\frac{1}{220}< \frac{1}{216}\)

\(\Rightarrow\frac{219}{220}>\frac{215}{216}\)

\(\Rightarrow\frac{-219}{220}< \frac{215}{216}\)

Vậy:....

( Tự dưng thấy dài dài.... Ko biết cách sau được ko: -219/220 là p/s âm; 215/216 là p/s dương nên -219/220<215/216)

(Các câu khác tương tự, đỡ mất thời gian của mik)

bn nào giúp đi

\(\frac{149-x}{26}+\frac{171-x}{24}+\frac{189-x}{22}+\frac{203-x}{20}=10\)

\(\left(\frac{149-x}{26}-1\right)+\left(\frac{171-x}{24}-2\right)+\left(\frac{189-x}{22}-3\right)+\left(\frac{203-x}{20}-4\right)=0\)

\(\frac{123-x}{26}+\frac{123-x}{24}+\frac{123-x}{22}+\frac{123-x}{20}=0\)

\(\left(123-x\right)\left(\frac{1}{26}+\frac{1}{24}+\frac{1}{22}+\frac{1}{20}\right)=0\)

\(123-x=0\left(vì\frac{1}{26}+\frac{1}{24}+\frac{1}{22}+\frac{1}{20}\ne0\right)\)

\(\Rightarrow x=123\)

\(\frac{42+y}{72}=\frac{153}{171}\)

\(\Rightarrow\left(42+y\right)\times171=76\times153\)

\(\Rightarrow\left(42+y\right)\times171=11628\)

\(\Rightarrow42+y=11628:171=68\)

\(\Rightarrow y=68-42=26\)

\(\frac{42+y}{76}=\frac{153}{171}\Rightarrow171\left(42+y\right)=153.76\Rightarrow7182+171y=11628\Rightarrow171y=4446\Rightarrow y=26\)

Vậy y = 26

\(\frac{42+y}{76}=\frac{153}{171}\)

\(\left(42+y\right).171=153.76\)

\(\left(42+y\right).171=11628\)

\(42+y=11628:171\)

\(42+y=68\)

\(y=68-42\)

\(y=26\)

\(\)

Đáp án là D

Ta có: 171 + [(-53) + 96 + (-171)] = 171 + (-53) + 96 + (-171) = [171 + (-171)] + (-53) + 96

     = 0 + (-53) + 96 = (-53) + 96 = 43

Đáp án cần chọn là: D