\(2x^3+15=31\)

=>\(2x^3=31-15=16\)

=>\(x^3=8\)

=>\(x=\sqrt[3]{8}=2\)

nếu có lỗi thì bảo mik nhé :>>

a) 2x - 31 + 42 = - 3x - 45

2x + 11 = - 3x - 45

2x + 3x = - 45 - 11

5x = - 56

x = - 56/5

b) - 25 + 2x = 15 + 17 - x

2x + x = 32 + 25

3x = 57

x = 19

`a)1/2+[-1]/[-3]-5/12 < 2x < 12/[-31]+136/31`

`186/372+124/372-155/372 < [744x]/372 < [-144]/372+1632/372`

`186+124-155 < 744x < -144+1632`

`155 < 744x < 1488`

`155:744 < 744x:744 < 1488:744`

`5/24 < x < 2`

Vậy `5/24 < x < 2`

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`b)[-2]/5 < x/15 < 1/6`

`[-12]/30 < [2x]/30 < 5/30`

`-12 < 2x < 5`

`-12:2 < 2x:2 < 5:2`

`-6 < x < 5/2`

Vậy `-6 < x < 5/2`

Giải:

a) x - \(\dfrac{9}{25}\)= \(\dfrac{16}{25}\)

x = \(\dfrac{16}{25}\)+\(\dfrac{9}{25}\)
x = \(\dfrac{25}{25}\)

x = 1

b) \(\dfrac{-12}{30}\)<\(\dfrac{x}{30}\)<\(\dfrac{5}{30}\)

=> x có thể bằng \(\dfrac{-11}{30}\) đến \(\dfrac{4}{30}\)
=> x bằng -5; -4; -3; -2; -1;0;1;2

Lời giải:

a.

$=-37-x-23+15=-x-(37+23)+15=-x-60+15=-x-(60-15)=-x-45$

b.

$=176-176+x-42=0+x-42=x-42$

c.

$=1270-1270+2x+31=0+2x+31=2x+31$

d.

$=2x-141-231+461=2x-(141+231)+461=2x-372+461$

$=2x+(461-372)=2x+89$

a -11

b 4

c 4

\(a,3x-31=-40\Rightarrow3x=-9\Rightarrow x=-3\)

\(b,-3x+37=\left(-4\right)^2\Rightarrow-3x=-21\Rightarrow x=7\)

\(c,\left|2x+7\right|=5\)

\(\Rightarrow\left\{{}\begin{matrix}2x+7=5\Rightarrow x=-1\\2x+7=-5\Rightarrow x=-6\end{matrix}\right.\)

\(d,-x+21=15+2x\Rightarrow3x=6\Rightarrow x=2\)

a) Ta có: 3x-31=-40

\(\Leftrightarrow3x=-9\)

hay x=-3

Vậy: x=-3

b) Ta có: \(-3x+37=\left(-4\right)^2\)

\(\Leftrightarrow-3x+37=16\)

\(\Leftrightarrow-3x=16-37=-21\)

hay x=7

Vậy: x=7

a, x = -8 - 3 = -11

b, 35 + x = 27 + 12 = 39

=> x = 39 - 35 = 4

c, 2^x = 31 - 15 = 16 

=> x = 4

\(a\)) \(3+x=-8\)

\(x=-8-3\)

\(x=-11\)