Question

 \(A\left(3x-4\right)^2-4\left(x+1\right)^2=0\)              \(Bx^4+2x^3-3^2-8x-4=0\)  giải dùm tớ hai bài này nhá miinh se tick cho ai nhanh nhat

 

Answer 1

\(A=\left(3x-4\right)^2-4\left(x+1\right)^2=0\)

\(\Rightarrow\left(3x-4\right)^2-2^2\left(x+1\right)^2=0\)

\(\Rightarrow\left(3x-4\right)^2-\left(2x-2\right)^2=0\)

\(\Rightarrow\left(3x-4-2x+2\right)\left(3x-4+2x-2\right)=0\)

\(\Rightarrow\left(x-2\right)\left(5x-6\right)=0\)

\(\Rightarrow\orbr{\begin{cases}x-2=0\\5x-6=0\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=2\\x=\frac{6}{5}\end{cases}}\)