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a) \(x+\frac{1}{5}-\frac{2}{7}=4\frac{1}{2}\)
=> \(x+\frac{1}{5}-\frac{2}{7}=\frac{9}{2}\)
=> \(x=\frac{9}{2}+\frac{2}{7}-\frac{1}{5}=\frac{321}{70}\)
b) \(1\frac{3}{4}+x-\frac{7}{8}=5\)
=> \(\frac{7}{4}+x-\frac{7}{8}=5\)
=> \(\frac{7}{4}+x=\frac{47}{8}\)
=> \(x=\frac{33}{8}\)
c) \(\frac{1}{2}-\frac{1}{3}\cdot x=\frac{3}{4}\)
=> \(\frac{1}{3}\cdot x=\frac{1}{2}-\frac{3}{4}=-\frac{1}{4}\)
=> \(x=\left(-\frac{1}{4}\right):\frac{1}{3}=\left(-\frac{1}{4}\right)\cdot3=-\frac{3}{4}\)
a: =>x+1/5-27/10=11/2
=>x-5/2=11/2
hay x=8
b: =>11/4+x-7/8=6
=>15/8+x=6
hay x=33/8
X + 1/2 = 4 1/2 + 2,7 1 3/4 + X = 5 + 7/8
X + 1/2 = 7,2 1 3/4 + X = 5,875
X = 7,2 + 1/2 X = 5,875 - 1 3/4
X = 7,7 X = 4,125
Số số hạng x là :
( 20 - 2 ) : 2 + 1 = 10 ( số )
Tổng 2+4+6+...+20 là:
( 20 + 2 ) x 10 : 2 = 110
Ta có :
( x + x + x + ....+ x ) + ( 2 + 4 + 6 + .....+ 20 ) = 155
hay
10 x X + 110 = 155
10 x X = 155 - 110
10 x X = 45
x = 45 : 10
x = 4,5
nếu đúng thì chọn câu trả lời của mk nha bn ^^
a)\(\dfrac{2}{3}.\dfrac{4}{5}+\dfrac{1}{3}.\dfrac{4}{5}=\left(\dfrac{2}{3}+\dfrac{1}{3}\right).\dfrac{4}{5}=1.\dfrac{4}{5}=\dfrac{4}{5}\)
b)\(\dfrac{2}{3}.\dfrac{4}{5}-\dfrac{1}{3}.\dfrac{4}{5}=\left(\dfrac{2}{3}-\dfrac{1}{3}\right).\dfrac{4}{5}=\dfrac{1}{3}.\dfrac{4}{5}=\dfrac{4}{15}\)
a) \(\dfrac{2}{3}\times\dfrac{4}{5}+\dfrac{1}{3}\times\dfrac{4}{5}=\dfrac{4}{5}\times\left(\dfrac{2}{3}+\dfrac{1}{3}\right)=\dfrac{4}{5}\times1=\dfrac{4}{5}\)
b) \(\dfrac{2}{3}\times\dfrac{4}{5}-\dfrac{1}{3}\times\dfrac{4}{5}=\dfrac{4}{5}\times\left(\dfrac{2}{3}-\dfrac{1}{3}\right)=\dfrac{4}{5}\times\dfrac{1}{3}=\dfrac{4}{15}\)
c) \(\dfrac{1}{2}:\dfrac{3}{4}+\dfrac{1}{6}:\dfrac{3}{4}=\dfrac{1}{2}\times\dfrac{4}{3}+\dfrac{1}{6}\times\dfrac{4}{3}=\dfrac{4}{3}\times\left(\dfrac{1}{2}+\dfrac{1}{6}\right)=\dfrac{4}{3}\times\dfrac{2}{3}=\dfrac{8}{9}\)
d) \(\dfrac{1}{2}:\dfrac{3}{4}-\dfrac{1}{6}:\dfrac{3}{4}=\dfrac{1}{2}\times\dfrac{4}{3}-\dfrac{1}{6}\times\dfrac{4}{3}=\dfrac{4}{3}\left(\dfrac{1}{2}-\dfrac{1}{6}\right)=\dfrac{4}{3}\times\dfrac{1}{3}=\dfrac{4}{9}\)
a, \(x-\frac{1}{5}-\frac{2}{7}=4\frac{1}{2}\)
\(\Leftrightarrow x-\frac{17}{35}=\frac{9}{2}\)
\(\Leftrightarrow x=\frac{9}{2}+\frac{17}{35}\)
\(\Leftrightarrow x=\frac{349}{70}\)
b, \(1\frac{3}{4}+x-\frac{7}{8}=5\)
\(\Leftrightarrow\frac{7}{4}+x-\frac{7}{8}=5\)
\(\Leftrightarrow\frac{7}{8}+x=5\)
\(\Leftrightarrow x=5-\frac{7}{8}\)
\(\Leftrightarrow x=\frac{33}{8}\)
\(a,\dfrac{2}{5}\times4+x=2\dfrac{2}{5}\\ \Rightarrow\dfrac{8}{5}+x=\dfrac{12}{5}\\ \Rightarrow x=\dfrac{12}{5}-\dfrac{8}{5}\\ \Rightarrow x=\dfrac{4}{5}\\ b,155\times2,7-x=98,3\\ \Rightarrow418,5-x=98,3\\ \Rightarrow x=418,5-98,3\\ \Rightarrow x=320,2\)
a) \(\dfrac{2}{5}\)x 4 + X = \(2\dfrac{2}{5}\)
\(\dfrac{8}{5}\) + X = \(\dfrac{12}{5}\)
X = \(\dfrac{12}{5}\)- \(\dfrac{8}{5}\)
X = \(\dfrac{4}{5}\)
b) 155 x 2,7 - X = 98,3
418,5 - X = 98,3
X = 418,5 - 98,3
X = 320,2