mk sắp phải đi học rồi các bạn giúp mình với có đc ko mk nhớ sẽ đền đáp công ơn của bạn 

a) (5 - x) +12 = -25

<-> 5 - x + 12 = -25

<-> 17 - x = - 25

<-> x = 42

b) 12 - 4(x - 2) = -4

<-> 12 - 4x + 8 = -4

<-> 20 - 4x = -4

<-> 4x = 24

<-> x = 6

\(135-5\cdot\left(x+4\right)=35\)

\(5\cdot\left(x+4\right)=135-35\)

\(5\cdot\left(x+4\right)=100\)

\(x+4=100:5\)

\(x+4=20\)

\(x=20-4\)

\(x=16\)

b) \(25+3\cdot\left(x-8\right)=106\)

\(3\cdot\left(x-8\right)=106-25\)

\(3\cdot\left(x-8\right)=81\)

\(x-8=81:3\)

\(x-8=27\)

\(x=27+8\)

\(x=35\)

c) \(3^2\cdot\left(x+4\right)-5^2=5\cdot2^2\)

\(9\cdot\left(x+4\right)-25=5\cdot4\)

\(9\cdot\left(x+4\right)-25=20\)

\(9\cdot\left(x+4\right)=20+25\)

\(9\cdot\left(x+4\right)=45\)

\(x+4=45:9\)

\(x+4=5\)

\(x=5-4\)

\(x=1\)

Chúc bạn học tốt!!!!!!!!!!!!!!!!!!!!

14-3x=-x+4<=>x=10

2(x+2)+7=x-25<=>2x+4+7=x-25<=>2x-x=-25-11=-36<=>x=-36

Ta có \(x^2+4^2=25\)

\(x^2+16=25\)

\(x^2=25-16=9\)

\(x^2=9\) 

\(x^2=9=3^2=\left(-3\right)^2\)

Vậy x=3 và x=-3

Ta có:   x² + 4² = 25

    \(\Rightarrow\)x² = 25 - 4²  = 9

    \(\Rightarrow\)x = \(\pm\)\(\sqrt{9}\)=  \(\pm\)3

Vậy x = \(\pm\)3

a/ \(4^x=2^{x+1}\)

\(\Leftrightarrow\left(2^2\right)^x=2^{x+1}\)

\(\Leftrightarrow2^{2x}=2^{x+1}\)

\(\Leftrightarrow2x=x+1\)

\(\Leftrightarrow2x-x=1\)

\(\Leftrightarrow x=1\left(tm\right)\)

Vậy .....

b/ \(16=\left(x-1\right)^4\)

\(\Leftrightarrow\left[{}\begin{matrix}\left(x-1\right)^4=4^4\\\left(x-1\right)^4=\left(-4\right)^4\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x-1=4\\x-1=-4\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=5\\x=-3\end{matrix}\right.\)

Vậy ...

c/ bí

b) 16 = ( x - 1 )⁴

2⁴ = ( x - 1 )⁴

\(\Rightarrow\) 2 = x - 1

\(\Leftrightarrow\) x - 1 = 2

x = 2 + 1

x = 3

x=-\(\dfrac{-71}{25}\)

\(6\frac{1}{4}x-5\frac{1}{2}x=25\%\)

\(\left(6\frac{1}{4}-5\frac{1}{2}\right)x=\frac{1}{4}\)

\(\frac{3}{4}.x=\frac{1}{4}\)

\(\Rightarrow x=\frac{1}{4}:\frac{3}{4}\)

\(\Rightarrow x=\frac{1}{3}\)

25/4x - 11/2x=1/4

(25/4 - 11/2)x = 1/4

(25/4 -22/4)x=1/4

3/4x=1/4

x=1/4:3/4

x=1/3

sorry pạn nhìu!xin hiểu hộ mình 1/3 hay1/4...là phân số nha!

a) x- 25%x= 1/2<=>x-1/4x=1/2<=>3/4x=1/2<=>x=1/2:3/4=2/3

b)\(\left(50\%x+2\frac{1}{4}\right).\frac{-2}{3}=\frac{17}{6}\Leftrightarrow-\frac{1}{3}x-\frac{3}{2}=\frac{17}{6}\Leftrightarrow x=-13\)

c)\(\left(3\frac{x}{7}+1\right):\left(-4\right)=\frac{-1}{28}\Leftrightarrow\frac{28+x}{7}:\left(-4\right)=\frac{-1}{28}\Leftrightarrow\frac{28+x}{-28}=\frac{1}{-28}\Leftrightarrow28+x=1\Leftrightarrow x=-27\)

d)\(\left(1\frac{1}{3}-25\%-\frac{5}{12}\right)-2x=1,6:\frac{3}{5}\Leftrightarrow\frac{2}{3}-2x=\frac{8}{3}\Leftrightarrow x=-1\)

a)x-25%x=1/2

x-1/4x=1/2

x.(1-1/4)=1/2

x.3/4=1/2

x=1/2:3/4

x=2/3