ĐKXĐ: \(\left\{{}\begin{matrix}x\ge1\\\frac{-1-\sqrt{5}}{4}\le x\le-\frac{1}{8}\end{matrix}\right.\)(Có thể chưa chính xác)

\(12x^2+16x+1=2\sqrt{24x^3+12x^2-6x}+4\sqrt{x^2-x}+4\sqrt{8x^3+9x^2+x}\)

Áp dụng AM-GM:

\(2\sqrt{24x^3+12x^2-6x}=2\sqrt{6x\left(4x^2+2x-1\right)}\le6x+\left(4x^2+2x-1\right)=4x^2+8x-1\left(1\right)\)

\(4\sqrt{x^2-x}=2\sqrt{1.\left(4x^2-4x\right)}\le4x^2-4x+1\left(2\right)\)

\(4\sqrt{8x^3+9x^2+x}=2\sqrt{\left(4x^2+4x\right)\left(8x+1\right)}\le\left(4x^2+4x\right)+\left(8x+1\right)=4x^2+12x+1\left(3\right)\)

Cộng \(\left(1\right),\left(2\right),\left(3\right)\), ta có: \(VP\le VT\)

Dấu ''='' xảy ra khi :

\(\left\{{}\begin{matrix}4x^2+2x-1=6x\\4x^2-4x=1\\4x^2+4x=8x+1\end{matrix}\right.\)\(\Rightarrow4x^2-4x-1=0\)

\(\Rightarrow x=\frac{1\pm\sqrt{2}}{2}\) (t/m ĐKXĐ)

b: \(\Leftrightarrow32x^5+1-32x^5+1=2\)

=>2=2(luôn đúng)

a: \(\Leftrightarrow\left[\left(x-3\right)^2-\left(x+3\right)^2\right]\left[\left(x-3\right)^2+\left(x+3\right)^2\right]+24x^3=216\)

\(\Leftrightarrow-12x\left(2x^2+18\right)+24x^3=216\)

=>-216x=216

hay x=-1

Tìm GTNN của biểu thức :

\(x^2+2x+4\)

Đặt A = \(x^2+2x+4\)

\(\Leftrightarrow A=\left(x^2+2.x.1+1\right)+3\)

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

Ta luôn có : \(\left(x+1\right)^2\ge0\forall x\)

Suy ra : \(\left(x+1\right)^2+3\ge3\forall x\)

Hay A\(\ge3\) với mọi x

Dấu "=" xảy ra khi \(x+1=0\Rightarrow x=-1\)

Nên : \(A_{min}=3khix=-1\)

\(x^3-x^2-x-2=0\)

\(\Leftrightarrow x^3-2x^2+x^2-2x+x-2=0\Rightarrow\left(x-2\right).\left(x^2+x+1\right)=0\)

\(x^2+x+1=x^2+2\cdot\frac{1}{2}\cdot x+\frac{1}{4}+\frac{3}{4}=\left(x+\frac{1}{2}\right)^2+\frac{3}{4}>0\)

\(x^2+x+1\ne0\Rightarrow x-2=0\Rightarrow x=2\)

\(x^9-8x^3+16x^2-2x+2012\)

\(2^9-8\cdot2^3+16\cdot2^2-2\cdot2+2012=2520\)

Vậy...

1.

đk: \(x\ge2\)

Đặt y = \(\sqrt{x+2}\) ta biến pt về dạng pt thuần nhất bậc 3 đối vs x và y:

ta có : \(x^3-3x^2+2y^3-6x=0\)

\(\Leftrightarrow x^3-3xy^2+2y^3=0\)

\(\Rightarrow\left\{{}\begin{matrix}x=y\\x=-2y\end{matrix}\right.\)

ta sẽ có nghiệm : \(x=2;x=2-2\sqrt{3}\)

\(1.đk:\left(x+2\right)^3\ge0\Leftrightarrow x\ge-2\)

\(pt\Leftrightarrow x^3-3x\left(x+2\right)+2\sqrt{\left(x+2\right)^3}=0\)

\(\Leftrightarrow x^3-x\left(x+2\right)+2\sqrt{\left(x+3\right)^2}-2x\left(x+2\right)=0\)

\(\Leftrightarrow x\left[x^2-\left(x+2\right)\right]+2\left(x+2\right)\left(\sqrt{x+2}-x\right)=0\)

\(\Leftrightarrow x\left[\left(x-\sqrt{x+2}\right)\left(x+\sqrt{x+2}\right)\right]+2\left(x+2\right)\left(\sqrt{x+2}-x\right)=0\)

\(\Leftrightarrow\left(\sqrt{x+2}-x\right)\left[-x\left(\sqrt{x+2}+x\right)+2\left(x+2\right)\right]=0\)

\(\Leftrightarrow\left(\sqrt{x+2}-x\right)^2\left(2\sqrt{x+2}+x\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}\sqrt{x+2}=x\left(2\right)\\2\sqrt{x+2}=-x\left(3\right)\end{matrix}\right.\)

\(\left(2\right)\Leftrightarrow\left\{{}\begin{matrix}x\ge0\\x^2=x+2\end{matrix}\right.\)\(\Leftrightarrow x=2\left(tm\right)\)

\(\left(3\right)\Leftrightarrow\left\{{}\begin{matrix}-x\ge0\Leftrightarrow x\le0\\x^2=4\left(x+2\right)\end{matrix}\right.\)\(\Leftrightarrow x=2-2\sqrt{3}\left(tm\right)\)

\(2.đk:x^2;y^2\ge2018\Leftrightarrow\left[{}\begin{matrix}x;y\le-\sqrt{2018}\\x;y\ge\sqrt{2018}\end{matrix}\right.\)

\(pt\Leftrightarrow\sqrt{x^2+11}-\sqrt{y^2+11}+\sqrt{x^2-2018}-\sqrt{y^2-2018}+x^2-y^2=0\)

\(\Leftrightarrow\left(x+y\right)\left(x-y\right)+\dfrac{x^2+11-y^2-11}{\sqrt{x^2+11}+\sqrt{y^2+11}}+\dfrac{x^2-2018-y^2+2018}{\sqrt{x^2-2018}+\sqrt{y^2-2018}}=0\)

\(\Leftrightarrow\left(x-y\right)\left(x+y\right)\left[1+\dfrac{1}{\sqrt{x^2+11}+\sqrt{y^2+11}}+\dfrac{1}{\sqrt{x^2-2018}+\sqrt{y^2+2018}}>0\right]=0\Leftrightarrow\left[{}\begin{matrix}x=y\\x=-y\end{matrix}\right.\)

\(x=y\Rightarrow M=x^{11}-x^{2018}\)

\(x=-y\Rightarrow M=-y^{11}-y^{2018}=:vvv\) (đến đây chịu)