=49 nha em

a: \(\left(4x^2+12xy+9y^2\right):\left(2x+3y\right)=\left(2x+3y\right)^2:\left(2x+3y\right)=2x+3y\)

d: \(\left(x^2+6xy+9y^2\right):\left(x+3y\right)=\left(x+3y\right)^2:\left(x+3y\right)=x+3y\)

e: \(\dfrac{64y^3-27}{4y-3}=\dfrac{\left(4y-3\right)\left(16y^2+12y+9\right)}{4y-3}=16y^2+12y+9\)

a, \(4x^2+12xy+9y^2=\left(2x+3y\right)^2\)

\(\Rightarrow\left(4x^2+12xy+9y^2\right):\left(2x+3y\right)\)

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

b,\(x^2+6xy+9y^2=\left(x+3y\right)^2\)

\(\Rightarrow\left(x^2+6xy+9y^2\right):\left(x+3y\right)\\ =\left(x+3y\right)^2:\left(x+3y\right)\\ =x+3y\)

c, \(64y^3-27=\left(4y-3\right)\left(16y^2+12y+9\right)\)

\(\Rightarrow\left(64x^3-27\right):\left(4y-3\right)\\ =\left[\left(4y-3\right)\left(16x^2+12x+9\right)\right]:\left(4y-3\right)\\ =16x^2+12x+9\)

\(\dfrac{2x-2xy-3+3y}{1-3y+3y^2-y^3}=\dfrac{2x\left(1-y\right)-3\left(1-y\right)}{\left(1-y\right)^3}\)

\(=\dfrac{\left(2x-3\right)\left(1-y\right)}{\left(1-y\right)^3}=\dfrac{2x-3}{\left(1-y\right)^2}\)

a) \(\left(2x^2-1\right)^2=\left(2x^2\right)^2-2.2x^2.1+1^2\)

\(=4x^4-4x^2+1\).

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

\(=\frac{1}{4}x^2+3y^2x+9y^4\)

Chúc bn hc tốt!

`8x^3 - 12x^{2} y + 6xy^2 - y^3 + 12x^2 - 12xy + 3y^2 + 11`

`=(8x^3 - 12x^{2}y + 6xy^{2} - y^{3}) + 3(4x^2 - 4xy + y^2) + 11`

`=(2x-y)^{3} + 3(2x-y)^2 + 11`

Thay `2x-y=9` vào `:`

`9^3 + 3 . 9^2 + 11`

`=729 + 243 + 11`

`=983`

A=8x^3-12x^2y+6xy^2-y^3+12x^2-12xy+3y^2+11

=(2x-y)^3+4(2x-y)^2+11

Khi 2x-y=9 thì A=9^3+4*9^2+11

=1064

\(\dfrac{2x}{3y}=-\dfrac{1}{3}\Rightarrow\dfrac{2x}{-1}=\dfrac{3y}{3}\)

áp dụng t/c của dãy tỉ số bằng nhau ta có:

\(\dfrac{2x}{-1}=\dfrac{3y}{3}=\dfrac{2x-3y}{-1-3}=\dfrac{7}{-4}\)

\(\dfrac{2x}{-1}=\dfrac{7}{-4}\Rightarrow x=\dfrac{7}{8}\\ \dfrac{3y}{3}=\dfrac{7}{-4}\Rightarrow y=-\dfrac{7}{4}\)

\(\dfrac{2x}{-1}=\dfrac{7}{-4}\Rightarrow2x=\dfrac{7}{-4}.-12x=\dfrac{-7}{-4}\Rightarrow2x=\dfrac{7}{4}\Rightarrow x=\dfrac{7}{4}:2\Rightarrow x=\dfrac{7}{8}\)

\(\dfrac{3y}{3}=\dfrac{7}{-4}\Rightarrow\dfrac{3}{3}.y=\dfrac{7}{-4}\Rightarrow1.y=\dfrac{7}{4}\Rightarrow y=\dfrac{7}{4}\)

\(a,\left(3x+5\right)^2=9x^2+30x+25\)

\(b,\left(2x-1\right)^3=8x^3-12x^2+6x-1\)

\(c,\left(3y+2x\right)\left(2x-3y\right)=4x^2-9y^2\)

Bài 2: 

a: \(A=\left(x+1\right)^3+5=20^3+5=8005\)

b: \(B=\left(x-1\right)^3+1=10^3+1=1001\)

Hình như sai đề .