12 I consider that to manage to know what other people are thinking is quite impossible

Tách riêng bài ra e nhé!

Có làm mới có ăn

Những cái loại không làm mà đòi có ăn thì ăn đầu bùi, ăn cức

Thế cho nó dễ.

2/3.x + 1/4 = 7/12

2/3.x           = 7/12 - 1/4

2/3.x           = 1/3

x                 = 1/3 : 2/3

x                 = 1/2

Bài làm

\(\frac{2}{3}x+\frac{1}{4}=\frac{7}{12}\)

\(\frac{2}{3}x=\frac{7}{12}-\frac{1}{4}\)

\(\frac{2}{3}x=\frac{7}{12}-\frac{3}{12}\)

\(\frac{2}{3}x=\frac{4}{12}\)

\(\frac{2}{3}x=\frac{1}{3}\)

\(x=\frac{1}{3}:\frac{2}{3}\)

\(x=\frac{1}{3}.\frac{3}{2}\)

\(x=\frac{1}{2}\)

Vậy \(x=\frac{1}{2}\)

2/3 .x + 1/4 = 7/12

2/3 .x         = 7/12 - 1/4

2/3.x          = 1/3

x                = 1/3 : 2/3

x                = 1/2

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

\(\Leftrightarrow-x^2+2x+x^2+6x+9=9\)

\(\Leftrightarrow8x=0\Leftrightarrow x=0\)

b) \(\Leftrightarrow x^2-8x+16-x^2+2x+3=-5\)

\(\Leftrightarrow-6x=-24\Leftrightarrow x=4\)

c) \(\Leftrightarrow\left(x-3\right)^2=0\)

\(\Leftrightarrow x-3=0\Leftrightarrow x=3\)

d) \(\Leftrightarrow\left(3x-2\right)^2=0\)

\(\Leftrightarrow3x-2=0\Leftrightarrow x=\dfrac{2}{3}\)

e) \(\Leftrightarrow\left(x-9-2x\right)\left(x-9+2x\right)=0\)

\(\Leftrightarrow-3\left(x+9\right)\left(x-3\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=-9\\x=3\end{matrix}\right.\)

f) \(\Leftrightarrow\left(5x-3-3x+5\right)\left(5x-3+3x-5\right)=0\)

\(\Leftrightarrow16\left(x+1\right)\left(x-1\right)=0\)

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

(3.4^x-5.12²):13 = 12

3.4^x-5.144 = 156

432.4^x-5 = 156

4^x-5 = 13/36

4^x : 4⁵ = 13/36

4^x = 13/36864

...

a) y-186=6*8

y-186=48

=> y= 48+186=234

b) 4*y:3=12

4*y=12*3

4*y=36

=> y= 36:4=9

a 234 , b 16

64 : 2^x+5 + 11 = 12

64 : 2^x+5 = 1

2^x+5 = 64 = 2⁶

=> x + 5 = 6

x = 1

64 : 2^x+5+11= 12

=> 64 : 2^x+5 = 1

=> 2^x+5 = 64 : 1 = 64 

=> 2^x+5 = 2⁶

=> x+5=6

=> x=1

64:2^x+5+11 = 12

=> 2^x+5=64:(12 - 11 )

=> 2^x+5= 64 = 2⁶

=> x+5=6

=> x =1