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Bài làm
= \(\frac{18.25+9.45.2+3.27.6}{100-99+98-97+96-95+.....+2-1}\)
= \(\frac{18.25+9.2.45+3.6.27}{50}\)
= \(\frac{18.25+18.45+18.27}{50}\)
= \(\frac{18.\left(25+45+27\right)}{50}\)
= \(\frac{18.97}{50}\)
= \(\frac{1746}{50}\)
\(\frac{864.48-432.96}{864.48.432}=\frac{864.48-432.2.48}{864.48.432}=\frac{864.48-864.48}{864.48.432}\)
\(=\frac{0}{864.48.432}=0\)
ta có tử số= 864.48-432.96=432.2.48-432.96=432.96-432.96=0
vậy phân thức đã cho có giá trị bằng 0
80/103 = 0,77
8/10 = 0,8
9/10 = 0,9
90/99 = 0,909
0,95 ; 90/99 ; 9/10 ; 8/10 ; 80/103
Gọi \(A=\frac{1}{1.4}+\frac{1}{4.7}+\frac{1}{7.10}+...+\frac{1}{22.25}\)
\(\Leftrightarrow\)\(3A=\frac{3}{1.4}+\frac{3}{4.7}+\frac{3}{7.10}+...+\frac{3}{22.25}\)
\(\Leftrightarrow\)\(3A=\frac{1}{1}-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+\frac{1}{7}-\frac{1}{10}+...+\frac{1}{22}-\frac{1}{25}\)
\(\Leftrightarrow\)\(3A=1-\frac{1}{25}\)
\(\Leftrightarrow\)\(3A=\frac{24}{25}\)
\(\Leftrightarrow\)\(A=\frac{24}{25}:3\)
\(\Leftrightarrow\)\(A=\frac{24}{25}.\frac{1}{3}\)
\(\Leftrightarrow\)\(A=\frac{8}{25}\)
Vậy \(A=\frac{8}{25}\)
Đặt \(C=\frac{1}{1.4}+\frac{1}{4.7}+...+\frac{1}{22.25}\)
\(\Rightarrow3C=\frac{3}{1.4}+\frac{3}{4.7}+\frac{3}{7.10}+....+\frac{3}{22.25}\)
\(\Rightarrow3C=1-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+\frac{1}{7}-\frac{1}{10}+...+\frac{1}{22}-\frac{1}{25}\)
\(\Rightarrow3C=1-\frac{1}{25}=\frac{24}{25}\)
\(\Rightarrow C=\frac{24}{25}:3=\frac{8}{25}\)
Vậy \(\frac{1}{1.4}+\frac{1}{4.7}+...+\frac{1}{22.25}=\frac{8}{24}\)
a) \(\frac{5}{1.4}+\frac{5}{4.7}+\frac{5}{7.10}+.....+\frac{5}{27.30}\)
\(=\frac{5}{3}\left(\frac{1}{1.4}+\frac{1}{4.7}+........+\frac{1}{27.30}\right)\)
\(=\frac{5}{3}\left(1-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+.....+\frac{1}{27}-\frac{1}{30}\right)\)
\(=\frac{5}{3}\left(1-\frac{1}{30}\right)\)
\(=\frac{5}{3}.\frac{29}{30}=\frac{29}{36}\)
Đặt \(A=\frac{12}{3\cdot5}+\frac{12}{5\cdot7}+\frac{12}{7\cdot9}+....+\frac{12}{97\cdot99}\)
\(2A=\frac{12}{3}-\frac{12}{5}+\frac{12}{5}-\frac{12}{7}+...+\frac{12}{97}-\frac{12}{99}\)
\(2A=\frac{12}{3}-\frac{12}{99}\)
\(A=\frac{128}{33}\cdot\frac{1}{2}=\frac{64}{33}\)
\(\frac{1}{2}:0,5-\frac{1}{4}:0,25+\frac{1}{8}:0,125+25\%+\frac{3}{4}\)
\(=1-1+1+1\)
\(=0+2=2\)
lưu ý là\(\frac{1}{2}=0,5\)
mấy số kia cũng bằng nhau nên chia ra cũng = 1
tính nhẩm được mà
\(\frac{26.27-212}{26.25+200}\)= \(\frac{702-212}{650+200}\)=\(\frac{490}{850}\)=\(\frac{49}{85}\)
nho k nhe
49/85 nha bn!