Question

Tìm x 

a) (x²+4)² - 4x(x²+4) = 0

Answer 1

\(\left(x^2+4\right)^2-4x\left(x^2+4\right)=0\)

\(\left(x^2+4\right)\left(x^2+4-4x\right)=0\)

\(\left(x^2+4\right)\left(x-2\right)^2=0\)

Th1:

\(x^2+4=0\)

mà \(x^2\ge0\)

=> loại

Th2:

x - 2 = 0

x = 2

Vậy x = 2

Answer 2

\(\left(x^2+4\right)^2-4x\left(x^2+4\right)=0\)

\(\Leftrightarrow\left(x^2+4\right)\left(x^2+4-4x\right)=0\)

\(\Leftrightarrow\left(x^2+4\right)\left(x+2\right)^2=0\)

Mà : \(x^2\ge0\Rightarrow x^2+4>0\)

\(\Rightarrow x-2=0\)

\(\Rightarrow x=2\)