Tìm x
a) 100-7×(X×5)=58
b)X×2/7=242/363×1616/2121
c)(23,58:19,5×X):22,5=3,128
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=> 10/7 = 2/7 . x
=> 2/7 . x = 10/7
=> x = 10/7 : 2/7
=> x = 5
242/363 + 1616/ 2121= 5/7 x y
\(\frac{2}{3}+\frac{16}{21}=\frac{5}{7}\)x y
\(\frac{14}{21}\)+\(\frac{16}{21}\)= \(\frac{5}{7}\)x y
\(\frac{10}{7}\)=\(\frac{5}{7}\)x y
\(\frac{10}{7}\): \(\frac{5}{7}\)=y
\(\frac{10}{7}\)x \(\frac{7}{5}\)=y
2=y
vậy y=2
\(\frac{242}{363}+\frac{1616}{2121}=\frac{5}{7}\times y\)
\(\frac{121\times2}{121\times3}+\frac{101\times16}{101\times21}=\frac{5}{7}\times y\)
\(\frac{2}{3}+\frac{16}{21}=\frac{5}{7}\times y\)
\(\frac{10}{7}=\frac{5}{7}\times y\)
\(\Rightarrow y=\frac{10}{7}:\frac{5}{7}\)
\(y=2\)
\(\left(\dfrac{242}{363}+\dfrac{1616}{2121}\right)=\dfrac{2}{7}.x\)
\(\Leftrightarrow\dfrac{242}{363}\left(1+\dfrac{8}{7}\right)=\dfrac{2}{7}.x\)
\(\Leftrightarrow\dfrac{242}{363}.\dfrac{15}{7}=\dfrac{2}{7}.x\)
\(\Leftrightarrow\dfrac{10}{7}=\dfrac{2}{7}.x\)
\(\Leftrightarrow x=\dfrac{10}{7}:\dfrac{2}{7}\)
\(\Leftrightarrow x=\dfrac{10}{7}.\dfrac{7}{2}\)
\(\Leftrightarrow x=5\)
` 242/363 + 1616/2121 = 2/7 xxy`
`2/7 xxy= 2/3 + 16/21`
`2/7 xxy= 14/21 +16/21`
`2/7 xxy= 30/21`
`y=10/7 : 2/7`
`y=10/7 xx 7/2`
`y=70/14`
`y=5`
__
` (y + 1/4) + (y + 1/16) + (y + 1/16) =2`
`(y+y+y)+(1/4 + 1/16+1/16)=2`
`3y + (4/16 +1/16 +1/16)=2`
`3y + 6/16=2`
`3y=2-6/16`
`3y= 32/16-6/16`
`3y= 26/16`
`y=26/16 : 3`
`y=26/48`
`y=13/24`
\(a,\dfrac{242}{363}+\dfrac{1616}{2121}=\dfrac{2}{7}\times y\)
\(\dfrac{2}{7}\times y=\dfrac{2\times121}{3\times121}+\dfrac{16\times101}{21\times101}\)
\(\dfrac{2}{7}\times y=\dfrac{2}{3}+\dfrac{16}{21}\)
\(\dfrac{2}{7}\times y=\dfrac{14}{21}+\dfrac{16}{21}\)
\(\dfrac{2}{7}\times y=\dfrac{30}{21}\)
\(\dfrac{2}{7}\times y=\dfrac{10}{7}\)
\(y=\dfrac{10}{7}:\dfrac{2}{7}\)
\(y=\dfrac{10}{7}\times\dfrac{7}{2}\)
\(y=5\)
\(---\)
\(b,\left(y+\dfrac{1}{4}\right)+\left(y+\dfrac{1}{16}\right)+\left(y+\dfrac{1}{16}\right)=2\)
\(\left(y+y+y\right)+\left(\dfrac{1}{4}+\dfrac{1}{16}+\dfrac{1}{16}\right)=2\)
\(3\times y+\left(\dfrac{4}{16}+\dfrac{2}{16}\right)=2\)
\(3\times y+\dfrac{6}{16}=2\)
\(3\times y+\dfrac{3}{8}=2\)
\(3\times y=2-\dfrac{3}{8}\)
\(3\times y=\dfrac{16}{8}-\dfrac{3}{8}\)
\(3\times y=\dfrac{13}{8}\)
\(y=\dfrac{13}{8}:3\)
\(y=\dfrac{13}{8}\times\dfrac{1}{3}\)
\(y=\dfrac{13}{24}\)
#\(Toru\)
\(\dfrac{242}{363}+\dfrac{1616}{2121}=\dfrac{2}{7}y\)
\(\dfrac{2\cdot121}{3\cdot121}+\dfrac{16\cdot101}{21\cdot101}=\dfrac{2}{7}y\)
\(\dfrac{2}{7}y=\dfrac{2}{3}+\dfrac{16}{21}\)
\(\dfrac{2}{7}y=\dfrac{10}{7}\)
\(y=\dfrac{10}{7}\div\dfrac{2}{7}=5\)
242/363 + 1616/2121 = 2/7 x a
10/7 = 2/7 x a
a = 10/7 : 2/7
a = 5
Bài làm
a)100-7.(X.5)=58
7.(X.5)=100-58
7.(X.5)=42
X.5=42:7
X.5=6
X =6:5
X=1,2.
#)Giải :
a) \(100-7\times\left(x\times5\right)=58\)
\(\Leftrightarrow7\times\left(x\times5\right)=42\)
\(\Leftrightarrow x\times5=6\)
\(\Leftrightarrow x=1,2\)
b) \(x\times\frac{2}{7}=\frac{242}{363}\times\frac{1616}{2121}\)
\(\Leftrightarrow x\times\frac{2}{7}=\frac{2}{3}\times\frac{16}{21}\)
\(\Leftrightarrow x\times\frac{2}{7}=\frac{32}{63}\)
\(\Leftrightarrow x=\frac{16}{9}\)