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A= -8/5: (1+2/3)
= -8/5:5/3
= -8/5.3/5
= -24/25
B= 7/5.15/49-22/15: 11/5
= 3/7-2/5
= 1/35
\(A=-1,6:\left(1+\frac{2}{3}\right)\)
\(A=-1,6:\frac{5}{3}\)
\(A=-\frac{24}{25}\)
\(B=1,4.\frac{15}{49}-\left(\frac{4}{5}+\frac{2}{3}\right):2\frac{1}{5}\)
\(B=\frac{135}{98}-\frac{2}{3}\)
\(B=\frac{209}{294}\)
= 25/49 *( 21/29-7/29) +24/49 * 15/29
=25/49*14/29+ 24/49*15/29
BẠN TỰ LÀM TIẾP NHA
study well
\(\frac{25}{49}.\frac{21}{29}-\frac{25}{49}.\frac{7}{29}+\frac{24}{49}.\frac{15}{29}\)
\(=\frac{25}{49}.\left(\frac{21}{29}-\frac{7}{29}\right)+\frac{24}{49}.\frac{15}{29}\)
\(=\frac{25}{49}.\frac{14}{29}+\frac{24}{49}.\frac{15}{29}\)
\(=\left(\frac{25}{49}+\frac{24}{49}\right).\left(\frac{14}{29}+\frac{15}{29}\right)\)
\(=1.1=1\)
50A=\(\left(\frac{49}{1}+.......+\frac{1}{49}\right)49:2\)
50A= 1201
A=1201:50
A=\(\frac{1201}{10}\)=120.1
mà 120,1 ko phải số tự nhiên mà là số thập phân
=>A ko là số tự nhiên
Ta có: \(P=\frac{1}{49}+\frac{2}{48}+\frac{3}{47}+...+\frac{48}{2}+\frac{49}{1}\)
\(\Rightarrow P=\left(1+\frac{1}{49}\right)+\left(1+\frac{2}{48}\right)+\left(1+\frac{3}{47}\right)+...+\left(1+\frac{48}{2}\right)+1\)
\(\Rightarrow P=\frac{50}{49}+\frac{50}{48}+\frac{50}{47}+...+\frac{50}{2}+\frac{50}{50}\)
\(\Rightarrow P=50\left(\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+...+\frac{1}{50}\right)\)
\(\Rightarrow\frac{S}{P}=\frac{\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+...+\frac{1}{50}}{50\left(\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+...+\frac{1}{50}\right)}=\frac{1}{50}\)
Vậy \(\frac{S}{P}=\frac{1}{50}\)
\(\frac{5}{8}+\frac{5}{27}-\frac{5}{49}\)
\(=5\left(\frac{1}{8}+\frac{1}{27}-\frac{1}{49}\right)\)
\(=\frac{1499}{10584}.5\)
\(=\frac{7495}{10584}\)
\(\frac{11}{8}+\frac{11}{27}-\frac{11}{49}\)
\(=11.\left(\frac{1}{8}+\frac{1}{27}-\frac{1}{49}\right)\)
\(=\frac{1499}{10584}.11\)
\(=1.557917611\)
F=(3/1.8+3/8.15+...+3/106.113)-(25/50.55+25/55.60+...+25/95.100) (1)
Đặt:
A=(3/1.8+3/8.15+3/15.22+...+3/106.113)
=3/7.(1-1/8+1/8-1/15+...+1/106-1/113)
=3/7.(1-1/113)
=3/7.112/113
=336/791. (2)
B=25/50.55+25/55.60+...+25/95.100
=25/5.(1/50-1/55+1/55-1/60+...+1/95-1/100)
=5.(1/50-1/100)
=1/20 (3)
Thay (2),(3) vào (1) ta được:
F=336/791-1/20
=5929/6720.
\(C=\frac{49}{1.8}+\frac{49}{8.15}+\frac{49}{15.22}+...+\frac{49}{141.148}\)
\(\Rightarrow\frac{1}{7}C=\frac{7}{1.8}+\frac{7}{8.15}+\frac{7}{15.22}+...+\frac{7}{141.148}\)
\(=1-\frac{1}{8}+\frac{1}{8}-\frac{1}{15}+\frac{1}{15}-\frac{1}{22}+...+\frac{1}{141}-\frac{1}{148}\)
\(=1-\frac{1}{148}=\frac{148}{148}-\frac{1}{148}=\frac{147}{148}\)
\(\Rightarrow C=\frac{147}{148}\div\frac{1}{7}=\frac{147}{148}.7=\frac{1029}{148}\)
Vậy \(C=\frac{1029}{148}.\)
=49(1/1.8 +1/8.15+..)
có
1/1.8= (1-1/8)
1/8.15=1/8-1/15
=> C=49*1/7*(1-1/8+1/8-1/15+...+1/141-1/148)
C=7*(1-1/148)=...
học tốt