Tính nhanh:
Chú ý: . = nhân
F=\(\frac{2007.2008+995}{2008.2008-1013}\)+ \(\frac{11.12+44.48+55.60}{22.24+88.96+110.120}\)
Giúp mk nha. Mk đang cần gấp lắm
Ai nhanh đúng mk tick. Mk hứa
O-O ^-^ <-> ♡-♡ ☆-☆ ¤-¤ ¡-¡
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\(\frac{11.12+33.36+55.60}{22.24+66.72+110.120}=\frac{11.12+33.36+55.60}{2.11.2.12+2.33.2.36+2.55.2.60}=\frac{11.12+33.36+55.60}{4.11.12+4.33.36+4.55.60}=\frac{11.12+33.36+55.60}{4.\left(11.12+33.36+55.60\right)}=\frac{1}{4.1}=\frac{1}{4}\)
a, \(A=\frac{6}{10.11}+\frac{6}{11.12}+\frac{6}{12.13}+...+\frac{6}{69.70}\)
\(A=\frac{6}{10}-\frac{6}{11}+\frac{6}{11}-\frac{6}{12}+\frac{6}{12}-\frac{6}{13}+...+\frac{6}{69}-\frac{6}{70}\)
\(A=\frac{6}{10}-\frac{6}{70}\)
\(A=\frac{18}{35}\)
b, \(B=\frac{4}{2.4}+\frac{4}{4.6}+\frac{4}{6.8}+...+\frac{4}{2018.2020}\)
\(B=\frac{4}{2}.\left(\frac{2}{2.4}+\frac{2}{4.6}+\frac{2}{6.8}+...+\frac{2}{2018.2020}\right)\)
\(B=2.\left(\frac{1}{2}-\frac{1}{4}+\frac{1}{4}-\frac{1}{6}+\frac{1}{6}-\frac{1}{8}+...+\frac{1}{2018}-\frac{1}{2020}\right)\)
\(B=2.\left(\frac{1}{2}-\frac{1}{2020}\right)\)
\(B=2.\frac{1009}{2020}\)
\(B=\frac{1009}{1010}\)
Chúc bạn học tốt
Hơi thắc mắc câu B cậu oi!!!Gỉai thích cho mk vs ạ!!Thanks
ta co:
\(\frac{11.12+22.24+44.48}{33.36+66.72+132.144}\)
\(=\frac{11.12+11.2.12.2+11.4.12.4}{33.36+33.2.36.2+33.4.36.4}\)
\(=\frac{11.12.\left(1+2.2+4.4\right)}{33.36.\left(1+2.2+4.4\right)}\)
\(=\frac{11.12}{36.33}\)
\(=\frac{1}{3.3}\)
\(=\frac{1}{9}\)
\(B=\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+...+\frac{1}{9900}\)
\(B=\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+...+\frac{1}{99.100}\)
\(B=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+...+\frac{1}{99}-\frac{1}{100}\)
\(B=1-\frac{1}{100}\)
\(B=\frac{99}{100}\)
\(B=\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+...+\frac{1}{9900}\)
\(=\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+...+\frac{1}{99.100}\)
\(=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+...+\frac{1}{99}-\frac{1}{100}\)
\(=1+\left(-\frac{1}{2}+\frac{1}{2}\right)+\left(-\frac{1}{3}+\frac{1}{3}\right)+\left(-\frac{1}{4}+\frac{1}{4}\right)+...+\left(-\frac{1}{99}+\frac{1}{99}\right)-\frac{1}{100}\)
\(=1-\frac{1}{100}=\frac{99}{100}\)
Câu trả lời là thế này, chắc chắn đúng:
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Mình không biết :PPPP
Đúng chưa ahihi