x nhân 2 cộng x nhân 8 =4200.
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\(x\times\frac{1}{2}\)\(+x\times\frac{1}{4}\)\(+x\times\frac{1}{8}\)\(=\frac{21}{24}\)
\(x\times\frac{1}{2}\)\(+x\times\frac{1}{4}\)\(=\frac{21}{24}\)\(\div\frac{1}{8}\)
\(x\times\frac{1}{2}\)\(+x\times\frac{1}{4}\)\(=\frac{168}{24}\)
\(x\times\frac{1}{2}\)\(=\)\(\frac{168}{24}\div\frac{1}{4}\)
\(x\times\frac{1}{2}\)\(=\frac{1344}{24}\)
\(x=\frac{1344}{24}\div\frac{1}{2}\)
\(x=112\)
Nếu : 2 x X + 1 = 8
Thì : 4 x X + 1 = ?
Ta có:
2 x X + 1 = 8
2 x X = 8 - 1
2 x X = 7
X = 7 : 2
X = 3,5
Vậy X = 3,5 ...
Nên: 4 x 3,5 + 1
= 14 + 1
= 15
... Vậy: 4 x X + 1 = 15
~ Hok T ~
6 2/7 + 7 3/5 + 8 6/9 + 9 1/4 + 2/5 + 5/7 + 1/3 x 3/4 + 1967
= 44/7 + 38/5 + 78/9 + 37/4 + 2/5 + 5/7 + 1/3 + 1967
= ( 44/7 + 5/7 ) + ( 38/5 + 2/5 ) + ( 26/3 + 1/3 ) + ( 37/4 + 3/4 ) +1967
= 7 + 8 + 9 + 10 + 1967
= 15 + 9 + 10 + 1967
= 24 + 10 + 1967
= 34 + 1967
= 2001
X x 102 - X - X = 4200
X x 102 - X x 1 - X x 1 = 4200
X x ( 102 - 1 - 1 ) = 4200
X x 100 = 4200
X. = 4200 : 100
X = 42
x . 102 - x - x = 4200
x . 102 - x . 1 - x . 1 = 4200
x . (102 - 1 - 1) = 4200
x . 100 = 4200
x = 42
\(\left(\frac{1}{1.2.3}+\frac{1}{2.3.4}+...+\frac{1}{8.9.10}\right).x=\frac{23}{45}\)
\(\left(\frac{1}{1.2}-\frac{1}{2.3}+\frac{1}{2.3}-\frac{1}{3.4}+...+\frac{1}{8.9}-\frac{1}{9.10}\right).x=\frac{23}{45}\)
\(\left(\frac{1}{1.2}-\frac{1}{9.10}\right).x=\frac{23}{45}\)
\(\frac{22}{45}.x=\frac{23}{45}\)
\(x=\frac{23}{45}:\frac{22}{45}\)
\(x=\frac{23}{22}\)
\(\left(\frac{1}{1.2.3}+\frac{1}{2.3.4}+...+\frac{1}{8.9.10}\right)x=\frac{23}{45}\)
\(\Rightarrow\left(\frac{2}{1.2.3}+\frac{2}{2.3.4}+...+\frac{2}{8.9.10}\right).\frac{x}{2}=\frac{23}{45}\)
\(\Rightarrow\left(\frac{1}{1.2}-\frac{1}{2.3}+\frac{1}{2.3}-\frac{1}{3.4}+...+\frac{1}{8.9}-\frac{1}{9.10}\right)x=\frac{46}{45}\)
\(\Rightarrow\left(\frac{1}{1.2}-\frac{1}{9.10}\right)x=\frac{46}{45}\)
\(\Rightarrow\frac{22}{45}.x=\frac{46}{45}\Rightarrow x=\frac{46}{22}=\frac{23}{11}\)
a*x+a*y+b*x+b*y
= a*(x+y)+b*(x+y)
= a*(-17)+b*(-17) (vì x+y=-17)
=(-17)*(a+b)
=(-17)*(-2) (vì a+b=-2)
=34
\(x.2+x.8=4200\)
\(x\left(2+8\right)=4200\)
\(x.10=4200\)
\(x=420\)