\(\left(5x-4\right)^4-49x^2=0\)
\(\Rightarrow\left[\left(5x-4\right)^2\right]^2-\left(7x\right)^2=0\)
\(\Rightarrow\left[\left(5x-4\right)^2-7x\right]\left[\left(5x-4\right)^2+7x\right]=0\)
\(\Rightarrow\left(25x^2-47x+16\right)\left(25x^2-33x+16\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}25x^2-47x+16=0\\25x^2-33x+16=0\end{matrix}\right.\)
BẠN TỰ LÀM NỐT NHÉ.