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CÁCH LÀM NHƯ SAU :
(7/28 + 1/28) + 1/70 + 1/130 + 1/x.(x+3)
8/28 + 1/70 +1/130 +1/x.(x+3)
2/7+1/70+1/130+1/x.(x+3)
(20/70 +1/70)+1/130+1/x.(x+3)
3/10+1/130+1/x.(x+3)
39/130+1/130+1/x.(x+3)
4/13+1/x.(x+3)
Đến đây bn tự làm hộ mình vớ. chúc hok tốt k cho mình nhé
\(\frac{1}{4}+\frac{1}{28}+\frac{1}{70}+\frac{1}{130}+\frac{1}{x\left(x+3\right)}\)
\(=\frac{1}{1.4}+\frac{1}{4.7}+\frac{1}{7.10}+\frac{1}{10.13}+\frac{1}{x\left(x+3\right)}\)
\(=\frac{1}{3}\left(\frac{1}{1}-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+\frac{1}{7}-\frac{1}{10}+\frac{1}{10}-\frac{1}{13}+\frac{1}{x}-\frac{1}{x+3}\right)\)
\(=\frac{1}{3}\left(\frac{1}{1}-\frac{1}{13}+\frac{1}{x}-\frac{1}{x+3}\right)\)
\(=\frac{1}{3}\left(\frac{12}{13}+\frac{1}{x}-\frac{1}{x+3}\right)\)
\(=\frac{1}{3}.\frac{12}{13}+\frac{1}{3}.\frac{1}{x}-\frac{1}{3}.\frac{1}{x+3}\)
\(=\frac{4}{13}+\frac{1}{3x}-\frac{1}{3x+3}\)
\(=\frac{4}{13}+\frac{1}{3x}-\frac{1}{3x+3}\)
\(=\frac{4}{13}+\frac{1}{3x}=\frac{1}{3x+3}\)
\(=\frac{4}{13}+\frac{1}{3x}=\frac{1}{3x+3}\)
\(=\frac{4}{13}+\frac{1}{3x}=\frac{1}{3}.\frac{1}{x+3}\)
\(=\frac{4}{13}=\frac{1}{3}.\frac{1}{x+3}-\frac{1}{3x}\)
\(=\frac{4}{13}=\frac{1}{3}.\frac{1}{x+3}-\frac{1}{3}.\frac{1}{x}\)
\(=\frac{4}{13}=\frac{1}{3}\left(\frac{1}{x+3}-\frac{1}{x}\right)\)
\(=\frac{4}{13}:\frac{1}{3}=\frac{1}{x+1}-\frac{1}{x}\)
\(=\frac{12}{13}=\frac{1}{x+1}-\frac{1}{x}\)
\(=\frac{12}{13}=\frac{x-\left(x+1\right)}{\left(x+1\right)x}\)
\(=\frac{12}{13}=-\frac{1}{x^2+x}\)
\(\Leftrightarrow=12\left(x^2+x\right)=13.\left(-1\right)\)
\(=12\left(x^2+x\right)=-13\)
\(=x^2+x=-\frac{13}{12}\)
\(=x\left(x+1\right)=-\frac{13}{12}\)
.... Chiụ
\(\frac{9}{16}:\frac{27}{8}=\frac{3^2:3^3}{2^4:2^3}=\frac{\frac{1}{3}}{2}=\frac{1}{6}\)
b tương tự nha
\(\frac{9}{16}:\frac{27}{8}=\frac{9}{16}\cdot\frac{8}{21}=\frac{3\cdot3\cdot4\cdot2}{8\cdot2\cdot7\cdot3}=\frac{14}{3}\)
\(\frac{40}{7}:\frac{5}{14}=\frac{40}{7}\cdot\frac{14}{5}=\frac{4\cdot5\cdot2\cdot7\cdot2}{7\cdot5}=\frac{16}{1}=16\)
Chúc bạn học tốt
1)\(4\frac{1}{3}+2\frac{1}{3}=6\frac{2}{3}\)
2) \(\frac{5+x}{8}=\frac{14}{16}\)
\(\Rightarrow\left(5+x\right).16=8.14\)
\(\Rightarrow80+16x=112\)
\(\Rightarrow16x=112-80\)
\(\Rightarrow16x=32\)
\(\Rightarrow x=32\div16\)
\(\Rightarrow x=2\)
a/
\(1\frac{1}{2}x1\frac{1}{3}x1\frac{1}{4}x1\frac{1}{5}x1\frac{1}{6}=\frac{3}{2}x\frac{4}{3}x\frac{5}{4}x\frac{6}{5}x\frac{7}{6}=\frac{7}{2}=3\frac{1}{2}\)
b/
x=0; y=5
3 - ( 5\(\frac{3}{8}\)+ x - 7\(\frac{5}{24}\)) : 16\(\frac{2}{3}\)= 2
3 - ( \(\frac{43}{8}\)+ x - \(\frac{173}{24}\)) : \(\frac{50}{3}\)= 2
3 - ( \(\frac{43}{8}\)+ x - \(\frac{173}{24}\)) = 2 x \(\frac{50}{3}\)
3 - ( \(\frac{43}{8}\)+ x - \(\frac{173}{24}\)) = \(\frac{100}{3}\)
\(\frac{43}{8}\)+ x - \(\frac{173}{24}\)= 3 - \(\frac{100}{3}\)
\(\frac{43}{8}\)+ x - \(\frac{173}{24}\)= \(-\frac{97}{3}\)
\(\frac{43}{8}\)+ x = \(-\frac{97}{3}+\frac{173}{24}\)
\(\frac{43}{8}\)+ x = \(-\frac{201}{8}\)
x = \(-\frac{201}{8}-\frac{43}{8}\)
x = \(=-\frac{61}{2}\)
a,=25/6;7/6=25/6x6/7=25/7
b,=7/2x32/6=56/3
c,=17/5-11/10=34/10-11/10=23/10
d,=8/3+11/4=32/12+33/12=65/12
\(5+\frac{x}{8}=\frac{14}{16}\)
\(\frac{x}{8}=\frac{14}{16}-5\)
\(\frac{x}{8}=\frac{-33}{8}\)
\(x=-33\)
\(5+\frac{x}{8}=\frac{14}{16}\)
\(\Rightarrow\frac{x}{8}=5-\frac{14}{16}\)
\(\Rightarrow\frac{x}{8}=\frac{33}{8}\)
\(\Rightarrow x=33\)
tíc mình nha