Question

x+1 phần 3 + 3( 2x + 1) phần 4 = 2x + 3 ( x+ 1) phần 6 +7 + 12x phần 12

Answer 1

\(\dfrac{x+1}{3}\) + \(\dfrac{3\left(2x+1\right)}{4}\) = \(\dfrac{2x+3\left(x+1\right)}{6}\) +\(\dfrac{7+12x}{12}\)

\(\Leftrightarrow\)\(\dfrac{4\left(x+1\right)+9\left(2x+1\right)}{12}\)= \(\dfrac{2\left(2x+3\right)\left(x+1\right)+7+12x}{12}\)

\(\Leftrightarrow\) 4x + 4 + 18x + 9 = 4x² + 10x + 6 +7 +12

\(\Leftrightarrow\) -4x² + 4x + 18x - 10x = 6 + 7 + 12 - 4 - 9

\(\Leftrightarrow\) -4x² + 12x = 12

\(\Leftrightarrow\)x (-4x+12)=12

\(\Leftrightarrow\) \(\left[{}\begin{matrix}x=12\\-4x+12=12\Rightarrow-4x=0\Rightarrow x=0\end{matrix}\right.\)

Vậy S =\(\left\{12;0\right\}\)