Tìm x
a) x-4=8
b) x-9=18
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a) 32 : (3.x - 2) = 8
3x - 2 = 32 : 8
3x - 2 = 4
3x = 4 + 2
3x = 6
x = 6 : 3
x = 2
b) 75 : (x - 18) = 25
x - 18 = 75 : 25
x - 18 = 3
x = 3 + 18
x = 21
c) (15 - 6.x) . 243 = 729
15 - 6x = 729 : 243
15 - 6x = 3
6x = 15 - 3
6x = 12
x = 12 : 6
x = 2
d) 4.(x - 12) + 9 = 17
4(x - 12) = 17 - 9
4(x - 12) = 8
x - 12 = 8 : 4
x - 12 = 2
x = 2 + 12
x = 14
e) 20 - 2.(x + 4) = 4
2(x + 4) = 20 - 4
2(x + 4) = 16
x + 4 = 16 : 2
x + 4 = 8
x = 8 : 2
x = 4
`32: ( 3xx x -2)=8`
`3xx x-2=32:8`
`3xx x-2=4`
`3 xx x=4+2`
`3xx x=6`
`x=6:3`
`x=2`
__
`75 : (x-18) =25`
`x-18=75:25`
`x-18= 3`
`x=3+18`
`x=21`
__
`(15-6 xx x ) xx 243 =729`
`15-6 xx x = 729 : 243`
`15-6 xx x = 3`
`6 xx x=15-3`
`6 xx x=12`
`x=12:6`
`x=2`
__
`4 xx (x-12)+9=17`
`4 xx (x-12)=17-9`
`4 xx (x-12)= 8`
`x-12=8:4`
`x-12=2`
`x=2+12`
`x=14`
__
`20-2xx(x+4)=4`
`2xx(x+4)=20-4`
`2xx(x+4)=16`
`x+4=16:2`
`x+4=8`
`x=8-4`
`x=4`
a, -1
b, -9
Sơ đồ con đường |
Lời giải chi tiết |
Áp dụng quy tắc chia hết của số nguyên |
a , x .8 = − 8 ⇔ x = − 8 : 8 ⇔ x = − 1 b , − 9. x = 81 ⇔ x = 81 : − 9 ⇔ x = − 9 |
a: \(x+6\dfrac{1}{8}=8\)
=>\(x+\dfrac{49}{8}=\dfrac{64}{8}\)
=>\(x=\dfrac{64}{8}-\dfrac{49}{8}=\dfrac{15}{8}\)
b: \(\dfrac{11}{2}\cdot x=\dfrac{1}{5}:\dfrac{1}{3}\)
=>\(x\cdot\dfrac{11}{2}=\dfrac{1}{5}\cdot3=\dfrac{3}{5}\)
=>\(x=\dfrac{3}{5}:\dfrac{11}{2}=\dfrac{3}{5}\cdot\dfrac{2}{11}=\dfrac{6}{55}\)
c: \(x\cdot\dfrac{3}{5}+\dfrac{2}{5}\cdot x=\dfrac{4}{9}+\dfrac{1}{3}\)
=>\(x\left(\dfrac{3}{5}+\dfrac{2}{5}\right)=\dfrac{4}{9}+\dfrac{3}{9}\)
=>\(x\cdot1=\dfrac{7}{9}\)
=>\(x=\dfrac{7}{9}\)
\(x:\dfrac{13}{16}=\dfrac{5}{-8}\\ x=\dfrac{5}{-8}.\dfrac{13}{16}=\dfrac{65}{-128}\)
\(x.\dfrac{-1}{2}=\dfrac{-4}{5}\\ x=\dfrac{-4}{5}:\dfrac{-1}{2}=\dfrac{8}{5}\)
\(a,121-\left(115+x\right)=3x-\left(25-9-5x\right)-8\\ 121-115-x=3x-25+9+5x-8\\ 6-x=8x-24\\ 8x+x=-24-6\\ 9x=-30\\ x=-\dfrac{30}{9}=-\dfrac{10}{3}\\ ----\\ b,2^{x+2}.3^{x+1}.5^x=10800\\ \left(2.3.5\right)^x.2^2.3=10800\\ 30^x.12=10800\\ 30^x=\dfrac{10800}{12}=900=30^2\\ Vậy:x=2\)
`4.(3-x)^10=9(3-x)^8`
`=>(3-x)^{8}(4(3-x)^2-9)=0`
`=>` $\left[ \begin{array}{l}3-x=0\\(3-x)^2=\dfrac{9}{4}\end{array} \right.$
`=>` $\left[ \begin{array}{l}x=3\\3-x=\dfrac{3}{2}\\3-x=-\dfrac{3}{2}\end{array} \right.$
`=>` $\left[ \begin{array}{l}x=3\\x=\dfrac{3}{2}\\x=\dfrac{9}{2}\end{array} \right.$
Vậy `x=3` hoặc `x=3/2` hoặc `x=9/2`
`b,(x-1)^{x+3}=(x-1)^{x+1}`
`=>(x-1)^{x+1}[(x-1)^2-1]=0`
`=>` $\left[ \begin{array}{l}x-=1\\x-=-1\end{array} \right.$
`=>` $\left[ \begin{array}{l}x=2\\x=1\\x=0\end{array} \right.$
Vậy `x=0` hoặc `x=1` hoặc `x=2`
a, 3 + x = 8
x = 8 - 3
x = 5
b, x + 4 = 0
x = 0 - 4
x = - 4
c x + 8 = 3
x = 3 - 8
x = -5
d 2 + x = -10
x = -10 - 2
x = - 12
a, -x/4 = -9/x
=> -x.x = 4.(-9)
=> -x2 = -36
=> x2 = 36
=> x = + 4
vậy_
b, x/4 = 18/x + 1
=> x(x + 1) = 4.18
=> x(x + 1) = 72
=> x(x + 1) = 8.9
=> x = 8
vậy_
a)\(\frac{-x}{4}=\frac{-9}{x}\)
\(\Rightarrow-x\times x=-9\times4\)
\(\Rightarrow-x^2=-36\)
\(\Rightarrow x=6\)
`a) x - 24/8 = 8`
`x = 8 + 24/8`
`x = 11`
`b) 76/18 - x × 17/3 = 4/9`
`x × 17/3 = 76/18 - 4/9`
`x × 17/3 = 34/9`
`x = 34/9 : 17/3`
`x = 2/3`
x=12
x=27
tích mình nhé
a)
x - 4 = 8
x = 8 + 4
x = 12
b)
x - 9 = 18
x = 18 + 9
x = 27
k nha