4+2x(2x+4)=-x

4+4x^2+8x=-x

4x^2+8x+x+4=0

4x^2+9x+4=0

Ban tu phan h ra nua la xong nhe.

Chuyen thanh phuong trinh h nhe ban.

x^2-x-2=0

x^2-2x+x-2=0

x(x-2)+(x-2)=0

(x+1)(x-2)=0

\(\Rightarrow\hept{\begin{cases}x+1=0\\x-2=0\end{cases}\Rightarrow\hept{\begin{cases}x=-1\\x=2\end{cases}}}\)

(4-x)(2-x)=2(4-x)

8-4x-2x+x^2=8-2x

8-8-4x-2x+2x+x^2=0

-4x+x^2=0

x(-4+x)=0

\(\Rightarrow\hept{\begin{cases}x=0\\-4+x=0\end{cases}\Rightarrow\hept{\begin{cases}x=0\\x=4\end{cases}}}\)

(4 - x)(2 - x) = 2.(4 - x)

2 - x = 2.(4 - x) : (4 - x)

2 - x = 2

x = 2 - 2 

x = 0

x^3-x=x^2+x

x^3-x^2-x-x=0

x^3-x^2-2x=0

x^3-2x^2+x^2-2x=0

x^2(x-2)+x(x-2)=0

(x-2)(x^2+x)=0

x(x-2)(x+1)=0

Th1 : x=0

Th2 : x-2=0=>x=2

Th3 : x+1=0=>x=-1

\(x^2=a^2+b^2+ab\Rightarrow x^4=\left(a^2+b^2+ab\right)^2\)

<=>\(x^4=a^4+b^4+a^2b^2+3a^2b^2+2a^3b+2ab^3\)

<=>\(2x^4=2a^4+2b^4+2a^2b^2+6a^2b^2+4a^3b+4ab^3\)

<=>\(2x^4=a^4+b^4+\left(a^4+4a^3b+6a^2b^2+4ab^3+b^4\right)\)

<=>\(2x^4=a^4+b^4+\left(a+b\right)^4\)

<=>\(2x^4=a^4+b^4+c^4\)(đpcm)

Ta có;

(5x-2)^2=4(2-x)^2

(5x-2)^2=4(4-4x+x^2)

(5x-2)^2=16-16x+4x^2

(5x-2)^2=(4-2x)^2

5x-2=4-2x

5x+2x=2+4

7x=6

x=6/7

(5x-2)^2=4(2-x)^2

(5x-2)^2=4(4-4x+x^2)

(5x-2)^2=16-16x+4x^2

(5x-2)^2=4^2-16x+(2x)^2

(5x-2)^2=(4-2x)^2

5x-2=4-2x

5x+2x-2-4=0

7x-6=0

7x=6

x=6/7