\(2^{x+1}.3^y=12x\)

\(\Rightarrow\) \(2^{x+1}.3^y=\left(3.4\right)^x\)

\(\Rightarrow\) \(2^{x+1}.3^y=3^x.2^{2x}\)

\(\Rightarrow\) \(3^{y-x}=2^{x-1}\)

\(\Rightarrow\) \(y-x=x-1=0\)

\(\Rightarrow\) \(x=y=1\)

a)3y(2y-4)-2y(3y+5)=44
6y2-12y-(6y2+10y)=44
6y2-12y-6y2-10y=44
-22y=44
y=-2
Vậy y=-2
b)(12x-5)(4x-1)+(3x-7)(1-16x)=81
48x2-12x-20x+5+3x-48x2-7+112x=81
          83x-2=81
          83x    =81+2
          83x    =83
              x=1
          Vậy x=1
                                     Đấy nhé bạn,nhớ k cho mình nha.<3

ĐỀ BÀI HƠI SAI SỬA LẠI:

Tìm x, y biết a) 3y(2y-4)-2y(3y+5)=44

                     b)(12x-5)(4x-1)+(3x-7)(1-16x)=81

Bài 2: 

a: Ta có: \(2^{x+1}\cdot3^y=12^x\)

\(\Leftrightarrow2^{x+1}\cdot3^y=2^{2x}\cdot3^x\)

\(\Leftrightarrow\left\{{}\begin{matrix}x+1=2x\\x=y\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=1\\y=1\end{matrix}\right.\)

Đáp án A

a: \(12x^4y^3+12x^3y^3+3x^2y^3\)

\(=3x^2y^3\cdot4x^2+3x^2y^3\cdot4x+3x^2y^3\cdot1\)

\(=3x^2y^3\left(4x^2+4x+1\right)\)

\(=3x^2y^3\left(2x+1\right)^2\)

b: \(x^4+xy^3-x^3y-y^4\)

\(=\left(x^4+xy^3\right)-\left(x^3y+y^4\right)\)

\(=x\left(x^3+y^3\right)-y\left(x^3+y^3\right)\)

\(=\left(x^3+y^3\right)\left(x-y\right)\)

\(=\left(x+y\right)\left(x-y\right)\left(x^2-xy+y^2\right)\)