Question

(x + 1)(4x - 3) = (2x + 5)(1+x)

Answer 1

\(\left(x+1\right)\left(4x-3\right)=\left(2x+5\right)\left(1+x\right)\)

\(\Leftrightarrow4x^2+x-3=2x^2+7x+5\)

\(\Leftrightarrow2x^2-6x-8=0\)

\(\Leftrightarrow2x\left(x+1\right)-8\left(x+1\right)=0\)

\(\Leftrightarrow2\left(x+1\right)\left(x-4\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x+1=0\\x-4=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-1\\x=4\end{matrix}\right.\)

Vậy tập nghiệm của pt là:\(S=\left\{-1;4\right\}\)

Answer 2

\(\left(x+1\right)\left(4x-3\right)=\left(2x+5\right)\left(1+x\right)\)

\(\Rightarrow4x-3=2x+5\)

\(\Rightarrow2x=8\)

\(\Rightarrow x=4\)

Vậy x = 4