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X x 3 +X/2+X/4=\(1\frac{1}{2}\)
X(3+1/2+1/4)=3/2
X x 15/4=3/2
X =2/5
chúc bạn hok tốt!!!
X x 3 + X x \(\frac{1}{2}\)+ X x \(\frac{1}{4}\) = \(\frac{3}{2}\)
X x ( 3 + \(\frac{1}{2}\) + \(\frac{1}{4}\) ) = \(\frac{3}{2}\)
X x \(\frac{15}{4}\) = \(\frac{3}{2}\)
X = \(\frac{3}{2}\) : \(\frac{15}{4}\) = 0,4
X = 0,4
Học Tốt !!
a) ( 1/2-1/3-1/6).(1/2+2/3+3/4+...+2017/2018) + 3/4.x = 9/10
0.(1/2+2/3+3/4+...+2017/2018) + 3/4.x = 9/10
0+3/4.x = 9/10
3/4.x = 9/10
x = 9/10: 3/4
x = 6/5
b) x + ( 3/1.3+3/3.5+...+3/13.15) = 11/5
x + 3/2. ( 1-1/3 + 1/3 - 1/5 + ...+ 1/13 - 1/15) = 11/5
x + 3/2. ( 1-1/15) = 11/5
x + 3/2.14/15 = 11/5
x + 7/5 = 11/5
x = 11/5 - 7/5
x = 4/5
\(5\frac{3}{4}:3+2\frac{1}{4}\times\frac{1}{3}-\frac{3}{8}\)
\(=\frac{23}{4}\times\frac{1}{3}+\frac{9}{4}\times\frac{1}{3}-\frac{3}{8}\)
\(=\left(\frac{23}{4}+\frac{9}{4}\right)\times\frac{1}{3}-\frac{3}{8}\)
\(=8\times\frac{1}{3}-\frac{3}{8}\)
\(=\frac{8}{3}-\frac{3}{8}\)
\(=\frac{55}{24}\)
Ta có:
\(\frac{1}{2}\times\frac{2}{3}\times\frac{3}{4}\times...\times\frac{200}{201}\times x=\frac{1}{402}\)
\(\Rightarrow\frac{1}{201}\times x=\frac{1}{402}\Rightarrow x=\frac{1}{402}:\frac{1}{201}=\frac{1}{2}\)
Vậy x = 1/2.
k vs kb cho tớ nha!
1/2 . 2/3 . 3/4 .... . 200/201 . x = 1/402
\(\frac{1.2.3...200}{2.3.4...201}\). x = 1/402
1/201 . x = 1/402
x = 1/402 : 1/201
x = 1/2
\(A=\frac{1}{1+2}+\frac{1}{1+2+3}+\frac{1}{1+2+3+4}+...+\frac{1}{1+2+3+...+2009}\)
\(=\frac{1}{\frac{2\cdot\left(1+2\right)}{2}}+\frac{1}{\frac{3\cdot\left(3+1\right)}{2}}+\frac{1}{\frac{4\cdot\left(4+1\right)}{2}}+...+\frac{1}{\frac{2009\cdot\left(2009+1\right)}{2}}\)
\(=\frac{2}{2\cdot3}+\frac{2}{3\cdot4}+\frac{2}{4\cdot5}+...+\frac{2}{2009\cdot2010}\)
\(=2\cdot\left(\frac{1}{2\cdot3}+\frac{1}{3\cdot4}+\frac{1}{4\cdot5}+...+\frac{1}{2009\cdot2010}\right)\)
\(=2\cdot\left(\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+...+\frac{1}{2009}-\frac{1}{2010}\right)\)
\(=2\cdot\left(\frac{1}{2}-\frac{1}{2010}\right)\)
\(=1-\frac{1}{1005}\)
\(=\frac{1004}{1005}\)
1/1+2=3=1/1+2+2=6=1/1+2+3+4=10+3+6=19+1/1+2+3+4=29+3+6+10+19+2009=2076nếu mình làm sai thì nhớ chỉ dùm
nhớ kết bạn với mình nhé
Mình trình bày trong hình nhé ^^ Bn tham khảo ạ\(3\dfrac{2}{5}\cdot1\dfrac{4}{7}=\dfrac{17}{5}\cdot\dfrac{11}{7}=\dfrac{187}{35}\)
1/2* x+2/3=9/2
1/2 * x = 9/2 - 2/3
1/2 * x= 23/6
x= 23/6 : 1/2
x= 23/6 x 2= 23/3
___
1/2*x-1/3=2/3
1/2*x = 2/3 + 1/3
1/2 * x= 1
x= 1: 1/2
x= 2
____
1/4+3/4:x=3
3/4 : x = 3 - 1/4
3/4 : x= 11/4
x= 11/4 : 3/4
x= 11/3
\(\dfrac{1}{2}\)\(\times\)\(x\) + \(\dfrac{2}{3}\) = \(\dfrac{9}{2}\)
\(\dfrac{1}{2}\)\(\times\)\(x\) = \(\dfrac{9}{2}\) - \(\dfrac{2}{3}\)
\(\dfrac{1}{2}\)\(\times\)\(x\) = \(\dfrac{23}{6}\)
\(x\) = \(\dfrac{23}{6}\):\(\dfrac{1}{2}\)
\(x\) = \(\dfrac{23}{3}\)
\(\dfrac{1}{2}\)\(\times\)\(x\) - \(\dfrac{1}{3}\) = \(\dfrac{2}{3}\)
\(\dfrac{1}{2}\)\(\times\)\(x\) = \(\dfrac{2}{3}\) + \(\dfrac{1}{3}\)
\(\dfrac{1}{2}\times\)\(x\) = 1
\(x\) = 1 : \(\dfrac{1}{2}\)
\(x\) = 2
\(\dfrac{1}{4}\) + \(\dfrac{3}{4}\): \(x\) = 3
\(\dfrac{3}{4}\): \(x\) = 3 - \(\dfrac{1}{4}\)
\(\dfrac{3}{4}\):\(x\) = \(\dfrac{11}{4}\)
\(x\) = \(\dfrac{3}{4}\): \(\dfrac{11}{4}\)
\(x\) = \(\dfrac{3}{11}\)