5x( 1 - 2x ) - 3x( x + 18) = 0
<=>5x-10x2-3x2-54x=0
<=>-13x2+49x=0
<=>x(13x+49)=0
\(\Leftrightarrow\orbr{\begin{cases}x=0\\13x+49=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=0\\\frac{-49}{13}\end{cases}}}\)
tập nghiệm của pt đã cho là :{\(\frac{-49}{13}\);0}
5x(1-2x) - 3x(x+18) =0
5x-10x^2 -3x^2 -54x= 0
-13x^2 -49x=0
-x( 13x+49) =0
=> x=0 hoac 13x+49 =0
=> x=0 hoac x= -49/13
\(5x\left(1-2x\right)-3x\left(x+18\right)=0\)
\(\Leftrightarrow5x-10x^2-3x^2-54x=0\)
\(\Leftrightarrow-13x^2-49x=0\)
\(\Leftrightarrow\orbr{\begin{cases}x=0\\x=-\frac{49}{13}\end{cases}}\)
\(5x\left(1-2x\right)-3x\left(x+18\right)=0\)
\(\Rightarrow5x-10x^2-3x^2-54x=0\)
\(\Rightarrow5x-54x-\left(10x^2+3x^2\right)=0\)
\(\Rightarrow-49x-13x^2=0\)
\(\Rightarrow-49x=13x^2\)
\(\Rightarrow\frac{-49}{13}=\frac{x^2}{x}=x\)
5x(1-2x)-3x(x+18)=0
=>5x(1-2x)=3x(x+18)
=>5x1-5x2x=3xx+3x18
=>5x-10x\(^2\)=3x\(^2\)+54x
=>-10x\(^2\)-3x\(^2\)=54x-5x
=>-13x\(^2\)=49x
Chia cả hai vế cho x, ta được:-13x=49=>x=-3
Vậy x=-3
\(5x\left(1-2x\right)-3x\left(x+18\right)=0\)
\(\Leftrightarrow x\left[5.\left(1-2x\right)-3.\left(x+18\right)\right]=0\)
\(\Leftrightarrow x.\left(5-10x-3x-54\right)=0\)
\(\Leftrightarrow x\left(-13x-49\right)=0\)
\(\Leftrightarrow\hept{\begin{cases}x=0\\-13x-49=0\end{cases}\Leftrightarrow\hept{\begin{cases}x=0\\-13x=49\end{cases}}}\)
\(\Leftrightarrow\hept{\begin{cases}x=0\\x=\frac{-49}{13}\end{cases}}\)
Vậy \(S=\left\{0;-\frac{49}{13}\right\}\)
