9/4-yx5/6=1/2+2/3
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\(\frac{9}{4}-y.\frac{5}{6}=\frac{1}{2}+\frac{1}{3}\)
\(\frac{9}{4}-y.\frac{5}{6}=\frac{5}{6}\)
\(y.\frac{5}{6}=\frac{9}{4}-\frac{5}{6}\)
\(y.\frac{5}{6}=\frac{17}{12}\)
\(y=\frac{17}{12}:\frac{5}{6}\)
\(y=\frac{17}{10}\)
\(\frac{9}{4}\)- y x \(\frac{5}{6}\)= \(\frac{1}{2}\)+ \(\frac{2}{3}\) = \(\frac{9}{4}\)- \(\frac{1}{2}\)- \(\frac{2}{3}\)= y x \(\frac{5}{6}\)
y x \(\frac{5}{6}\)= \(\frac{13}{12}\)
y = \(\frac{13}{12}\)x \(\frac{6}{5}\)= \(\frac{13}{10}\)
y.5 + y : 1/2 + y : 1/3
= y.5 + y.2 + y.3
= y.(5 + 2 + 3)
= y.10
y x 5 + (2 + 4 + 6 +...+ 18) = 270
=> y x 5 + (18 + 2) x 9 : 2 = 270 (Công thức tính tổng)
=> y x 5 + 20 x 9 : 2 = 270
=> y x 5 + 180 : 2 = 270
=> y x 5 + 90 = 270
=> y x 5 = 270 - 90
=> y x 5 = 180
=> y = 180 : 5
=> y = 36
Vậy...
1: =1/8*9/4=9/32
2: =8/27*243/32=9/4
3: =(5/4*4/5)^5*(4/5)^2=16/25
4: \(=\left(-\dfrac{5}{6}\cdot\dfrac{6}{5}\right)^2\cdot\left(\dfrac{6}{5}\right)^2=\dfrac{36}{25}\)
5: \(=\left(-\dfrac{4}{3}\right)^3\cdot\left(\dfrac{3}{4}\right)^{10}=\left(-1\right)\left(\dfrac{3}{4}\right)^7=-\left(\dfrac{3}{4}\right)^7\)
6: \(=\left(\dfrac{1}{3}\cdot\dfrac{-9}{2}\right)^4\left(-\dfrac{9}{2}\right)^2=\left(-\dfrac{3}{2}\right)^4\cdot\dfrac{81}{4}=\dfrac{9}{4}\cdot\dfrac{81}{4}=\dfrac{729}{16}\)
8: =(0,2*5)^4*5^2=25
10: =-0,5^5*2^10
=-0,5^5*2^5*2^5
=-32
13: =(0,5*2)^2*2^2=4
3xz=y*x5
=>3z=5y
=>z/5=y/3
x/3=y/4 =>x/9=y/12
y/3=z/5 =>y/12=z/20
=>x/9=y/12=z/20
Áp dụng tính chất của DTSBN, ta được:
\(\dfrac{x}{9}=\dfrac{y}{12}=\dfrac{z}{20}=\dfrac{2x-3y+z}{2\cdot9-3\cdot12+20}=\dfrac{6}{2}=3\)
=>x=18; y=36; z=60
\(\frac{9}{4}-y.\frac{5}{6}=\frac{1}{2}+\frac{2}{3}\)
\(\frac{9}{4}-y.\frac{5}{6}=\frac{7}{6}\)
\(y.\frac{5}{6}=\frac{9}{4}-\frac{7}{6}\)
\(y.\frac{5}{6}=\frac{13}{12}\)
\(y=\frac{13}{12}:\frac{5}{6}\)
\(y=\frac{13}{10}\)
9 / 4 - y x 5 / 6 = 1 / 2 + 2 / 3
9 / 4 - y x 5 / 6 = 7 / 6
y x 5 / 6 = 13 /12
y = 13 /10