8/x = 20/15
tìm x trong mỗi trường hợp sau : a, 7/12+x/15=1/20 b,-7/x+8/15=-1/20
a) \(\frac{7}{12}+\frac{x}{15}=\frac{1}{20}\)
=> \(\frac{35}{60}+\frac{4x}{60}=\frac{3}{60}\)
=> 35 + 4x = 3
=> 4x = -32
=> x = -8
b) \(\frac{-7}{x}+\frac{8}{15}=\frac{-1}{20}\)(ĐK \(x\ne0\))
=> \(\frac{-7}{x}=\frac{-1}{20}-\frac{8}{15}\)
=> \(\frac{-7}{x}=\frac{-3}{60}-\frac{32}{60}\)
=> \(\frac{-7}{x}=\frac{-35}{60}\)
=> \(\frac{-7}{x}=\frac{-7}{12}\)
=> x = 12(TM)
có ai cjoiw Phai Phai ko
g) 15-(x-8) = 20 -(15-4)
TÍNH NHANH
a) 3/16 + 4/15 + 5/16 + 1/15
b) 6/7 x 8/15 x 7/6 x 15/16
c) 19/20 x 13/21 + 9/20 x 8/21
d) (1+ 10/15 ) x (1+ 1/16 ) x ( 1+ 1/17 ) x ( 1+ 1/18 )
MINK ĐANG CẦN GẤP
a) \(\frac{3}{16}+\frac{4}{15}+\frac{5}{16}+\frac{1}{15}\)
\(=\left(\frac{3}{16}+\frac{5}{16}\right)+\left(\frac{4}{15}+\frac{1}{15}\right)\)
\(=\frac{1}{2}+\frac{1}{3}\)
\(=\frac{5}{6}\)
b) \(\frac{6}{7}\times\frac{8}{15}\times\frac{7}{6}\times\frac{15}{16}\)
\(=\left(\frac{6}{7}\times\frac{7}{6}\right)\times\left(\frac{8}{15}\times\frac{15}{16}\right)\)
\(=1\times\frac{1}{2}=\frac{1}{2}\)
c) \(\frac{19}{20}\times\frac{13}{21}+\frac{9}{20}\times\frac{8}{21}\)
\(=\frac{19\times13}{20\times21}+\frac{9\times8}{20\times21}\)
\(=\frac{247}{420}+\frac{72}{420}\)
\(=\frac{319}{420}\)
tích cho chị nha
câu a) = 5/6
câu b = 1/2
câu c = 319/420
tìm x trong mỗi trường hợp sau :
a, 7/12+x/15=1/20
b,-7/x+8/15=-1/20
a, | x+6 |= (-7)+ |-20|
b, | 4-x |= (-6)+ |-15|
c, | x-8 |= (-4)+ |-20|
d, | 20-x |=15- |-4|
Ai làm nhanh nhất mình tích cho
A, | x + 6 |=(-7)+20
->| x + 6 | = 13
TH1: x + 6 =13
-> x=13-6
-> x=7
TH2: x + 6 = (-13)
-> x= (-13) - 6
-> x = -19.
Làm ttừng câu nhé bạn
B, | 4 - x | = (-6) + 15
-> | 4 - x | = 9
TH1: 4 - x = 9
-> x =-5
TH2: 4 - x = -9
-> x =13
C, |x-8|=(-4)+20
-> |x-8|=16
TH1: x - 8 =16
-> x=24
TH2: x - 8 =-16
-> x =-8
D, |20-x|=15-4
->|20-x|=11
TH1: 20 - x = 11
-> x= 9
TH2: 20 - x = -11
-> x = 31
-125 x (-8) + (-15) x 20
= 1000 + ( -300 )
= 700
HỌC TỐT !
\(\text{ -125 x (-8) + (-15) x 20}\)
\(=1000+\left(-300\right)\)
\(=700\)
- x + 20 = - ( - 15) - ( +8) + 13
- x + 20 = - ( - 15) - ( +8) + 13
20 - x = 15 - 8 + 13
20 - x = 7 + 13
20 - x = 20
x = 20 - 20
x=0
Vậy: x=0
( X - 20 ) x 8 - 15 = 49
( X - 20 ) × 8 - 15 = 49
( X - 20 ) × 8 = 49 + 15
( X - 20 ) × 8 = 64
X - 20 = 64 : 8
X - 20 = 8
X = 8 + 20
X = 28
Vậy X = 28
( X -20 ) x 8 - 15 = 49
( X - 20 ) x 8 = 49 + 15
( X - 20 ) x 8 = 64
( X - 20 ) = 64 : 8
X - 20 = 8
X = 8 + 20
X = 28
( X - 20 ) × 8 - 15 = 49
( X - 20 ) × 8 = 49 + 15
( X - 20 ) × 8 = 64
X - 20 = 64 : 8
X - 20 = 8
X = 8 + 20
X = 28
Vậy X = 28
Bài 8: tìm x
a) x + 10 = 20
b) 2 . x + 15 = 35
c) 3 ⋅ ( x + 2 ) = 15
d) 10 . x + 15 . 11 = 20 . 10
e) 4 . ( x + 2 ) = 3 . 4
f) 33 x + 135 = 26 . 9
g) 2 . x + 15 + 16 + 17 = 100
h) 2 . (x + 9 + 10 + 11) = 4 . 12 . 25
`@` `\text {Ans}`
`\downarrow`
`a)`
`x + 10 = 20`
`=> x = 20 -10`
`=> x = 10`
Vậy, `x = 10`
`b)`
`2 * x + 15 = 35`
`=> 2x = 35 - 15`
`=> 2x = 20`
`=> x = 20 \div 2`
`=> x = 10`
Vậy, `x = 10`
`c)`
`3 * ( x + 2 ) = 15`
`=> x + 2 = 15 \div 3`
`=> x + 2 = 5`
`=> x = 5 - 2`
`=> x = 3`
Vậy, `x = 3`
`d)`
`10 * x + 15 * 11 = 20 * 10`
`=> 10x + 165 = 200`
`=> 10x = 200 - 165`
`=> 10x = 35`
`=> x = 35 \div 10`
`=> x = 3,5`
Vậy,` x = 3,5`
`e)`
`4 * ( x + 2 ) = 3 * 4`
`=> x + 2 = 12 \div 4`
`=> x + 2 = 3`
`=> x = 3 - 2`
`=> x = 1`
Vậy,` x = 1`
`f)`
`33 x + 135 = 26 * 9`
`=> 33x + 135 = 234`
`=> 33x = 234 - 135`
`=> 33x = 99`
`=> x = 99 \div 33`
`=> x = 3`
Vậy, `x = 3`
`g)`
`2 * x + 15 + 16 + 17 = 100`
`=> 2x + 48 = 100`
`=> 2x = 100 - 48`
`=> 2x = 52`
`=> x = 52 \div 2`
`=> x =26`
`h)`
`2 * (x + 9 + 10 + 11) = 4 . 12 . 25`
`=> 2 * (x + 9 + 10 + 11) = 4*25*12`
`=> 2 * (x + 9 + 10 + 11) = 100*12`
`=> x + 9 + 10 + 11 = 100*12 \div 2`
`=> x + 30 = 600`
`=> x = 600 - 30`
`=> x = 570`
Vậy, `x = 570.`
a) \(x+10=20\Leftrightarrow x=10\)
b) \(2x+15=35\Leftrightarrow2x=20\Leftrightarrow x=10\)
c) \(3.\left(x+2\right)=15\Leftrightarrow x+2=5\Leftrightarrow x=3\)
d) \(10x+15.11=20.10\Leftrightarrow10x+165=200\Leftrightarrow10x=35\Leftrightarrow x=\dfrac{35}{10}=\dfrac{7}{2}\)
e) \(4.\left(x+2\right)=3.4\Leftrightarrow x+2=3\Leftrightarrow x=1\)
f) \(35x+135=26.9\Leftrightarrow35x=234-135\Leftrightarrow35x=99\Leftrightarrow x=\dfrac{99}{35}\)
g) \(2x+15+16+17=100\Leftrightarrow2x+48=100\Leftrightarrow2x=52\Leftrightarrow x=26\)
h) \(2.\left(x+9+10+11\right)=4.12.25\)
\(\Leftrightarrow x+30=2.12.25\)
\(\Leftrightarrow x=600-30\)
\(\Leftrightarrow x=570\)
\(\dfrac{x}{15}\)=\(\dfrac{-8}{20}\)
\(\dfrac{x}{15}=\dfrac{-8}{20}\\ \Rightarrow x=\dfrac{-8}{20}\times15\\ \Rightarrow x=-6\)