HÌnh gì ạ

\(b,x\left(x+1\right)\left(x+2\right)\left(x+3\right)+1=x\left(x+3\right)\left(x+1\right)\left(x+2\right)+1=\left(x^2+3x\right)\left(x^2+3x+3\right)+1\)Đặt \(x^2+3x+2=t\) ta có :

\(\left(t-1\right)\left(t+1\right)+1=t^2-1+1=t^2\)

\(\Leftrightarrow\left(x^2+3x+2\right)^2\)

mk nghĩ là 712 hoặc 695

Ta có :

\(\widehat{A}+\widehat{D}=180^o\Rightarrow\widehat{A}=180^o-\widehat{D}=180^o-100^o=80^o\)\(\Rightarrow\widehat{C}=360^o-\widehat{A}-\widehat{B}-\widehat{D}=360^o-80^o-140^o-100^o=40^o\)Vậy : \(x=80;y=40\)

ĐKXĐ \(x\ne2;x\ne-2;x\ne0\)\(A=\left(\dfrac{x^3}{x^3-4x}+\dfrac{6}{6-3x}+\dfrac{1}{x+2}\right):\left(x+2+\dfrac{10-x}{x+2}\right)\)\(=\left(\dfrac{x^2}{x\left(x+2\right)\left(x-2\right)}\dfrac{6}{3\left(x-2\right)}+\dfrac{1}{x+2}\right):\left(x-2+\dfrac{10-x}{x+2}\right)\)\(=\left(\dfrac{3x^2}{3x\left(x-2\right)\left(x+2\right)}-\dfrac{6.x\left(x+2\right)}{3x\left(x-2\right)\left(x+2\right)}+\dfrac{3x\left(x-2\right)}{3x\left(x-2\right)\left(x+2\right)}\right):\left(\dfrac{\left(x-2\right)\left(x+2\right)^23x}{3x\left(x-2\right)\left(x+2\right)}+\dfrac{\left(10-x\right)3x\left(x-2\right)}{3x\left(x-2\right)\left(x+2\right)}\right)\)\(=\dfrac{3x^2-6x^2-12x+3x-6}{3x\left(x^2-4\right)}.\dfrac{3x\left(x^2-4\right)}{3x^4+12x^3+12x^2-6x^3-24x^2-24x}=\dfrac{-3x^2-9x-6}{3x^4+6x^3-12x^2-24x}=\dfrac{-3\left(x^2+6x+2\right)}{-3\left(-x^4-2x^3+4x^2+8x\right)}=\dfrac{x^2+6x+2}{-x^4-2x^3+4x^2+8x}\)

\(A=\left(x-y\right)^2+\left(x+1\right)^2+\left(y-5\right)^2+2001\ge2001\)Vậy Min A = 2001 khi \(\left[{}\begin{matrix}\left(x-y\right)^2=0\\\left(x+1\right)^2=0\\\left(y-5\right)^2=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=y\\x=-1\\y=5\end{matrix}\right.\)