x-12=4
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Ta gọi vế \(\left(12\cdot2+12\cdot4+12\cdot6\right)\)là vế \(\left(1\right)\)
Ta gọi vế \(\left(2+4+...+12+14\right)\)là vế \(\left(2\right)\)
\(\left(1\right):\)\(12\cdot\left(2+4+6\right)=12\cdot12=144\)
\(\left(2\right):\)\(\frac{\left(14-2\right)}{2}+1=7\)( số )\(=\left(14+2\right)\cdot\frac{7}{2}=28\)
Vậy ta có \(:\)
\(A=\frac{144}{56}=2.5714\)
Đáp số : \(2.5714\)
![](https://rs.olm.vn/images/avt/0.png?1311)
12 x 4 + 12 x 2 -12 x 6=0
0 chưa cho số nào cũng bằng không
0 nha
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
1: Ta có: \(\dfrac{x+4}{4}+\dfrac{3x-7}{5}=\dfrac{7x+2}{20}\)
\(\Leftrightarrow5x+20+12x-28=7x+2\)
\(\Leftrightarrow17x-7x=2+8=10\)
hay x=1
2: Ta có: \(\dfrac{x}{6}+\dfrac{1-3x}{9}=\dfrac{-x+1}{12}\)
\(\Leftrightarrow\dfrac{6x}{36}+\dfrac{4\left(1-3x\right)}{36}=\dfrac{3\left(-x+1\right)}{36}\)
\(\Leftrightarrow6x+4-12x=-3x+3\)
\(\Leftrightarrow-6x+3x=3-4\)
hay \(x=\dfrac{1}{3}\)
3: Ta có: \(\dfrac{x-3}{3}-\dfrac{x+2}{12}=\dfrac{2x-1}{4}\)
\(\Leftrightarrow4x-12-x-2=6x-3\)
\(\Leftrightarrow3x-14-6x+3=0\)
\(\Leftrightarrow-3x=11\)
hay \(x=-\dfrac{11}{3}\)
4: Ta có: \(\dfrac{x-2}{4}-\dfrac{2x+3}{3}=\dfrac{x+6}{12}\)
\(\Leftrightarrow3x-6-8x-12=x+6\)
\(\Leftrightarrow-5x-x=6+18\)
hay x=-4
5: Ta có: \(\dfrac{2x-1}{12}-\dfrac{3-x}{18}=\dfrac{-1}{36}\)
\(\Leftrightarrow6x-3+2x-6=-1\)
\(\Leftrightarrow8x=8\)
hay x=1
![](https://rs.olm.vn/images/avt/0.png?1311)
Tính nhanh
Ạ) ( 12 x 2 + 12 x 4 - 12 x 6) : ( 2 + 4 + 6 +... + 12 + 14)
b) 37 x 49 + 37 x 2 x 25 + 37
![](https://rs.olm.vn/images/avt/0.png?1311)
A) (12 x 2 + 12 x 4 + 12 x 6) : ( 2 + 4 + 6 + ... + 12 + 14)
= [12 x ( 2 + 4 - 6 )] : ( 2 + 4 + 6 + ... + 12 + 14)
= [12 x 0 ] : ( 2 + 4 + 6 + ... + 12 + 14)
= 0 : ( 2 + 4 + 6 + ... + 12 + 14)
= 0
B) 37 x 49 + 37 x 2 x 25 + 37
= 37 x (49 + 2 x 25 + 1)
= 37 x 100
= 3700
Học dỏi nha :)))
~ Good luck ~
`x-12=4`
`=>x=4+12`
`=>x=16`
x-12=4
x =12 +4
x =16