tìm x biết
\(9\left(x+2\right)-3\left(x+2\right)=0\)
\(x\left(x+5\right)+\left(x-3\right)\left(x+5\right)=0\)\(3x^2+6x=0\)
\(2\left(2x-5\right)-3x=0\)
\(\left(x-1\right)^2+x\left(5-x\right)=0\)
\(\left(2x-3\right)\left(2x+3\right)-\left(x+5\right)^2-3\left(x-1\right)\left(x+2\right)\)=0
\(\left(2x-1\right)^2-45=0\)
\(2x^2-6x=0\)
giúp vs can gap
a. \(9\left(x+2\right)-3\left(x+2\right)=0\)
\(\Leftrightarrow9x+18-3x-6=0\)
\(\Leftrightarrow6x+12=0\)
\(\Leftrightarrow x=-2\)
e. \(\left(2x-1\right)^2-45=0\)
\(\Leftrightarrow4x^2-2x+1-45=0\)
\(\Leftrightarrow4x^2-2x-44=0\)
Đến đó tự giải tiếp nha!
c. \(2\left(2x-5\right)-3x=0\)
\(\Leftrightarrow4x-10-3x=0\)
\(\Leftrightarrow x-10=0\)
\(\Leftrightarrow x=10\)
g. \(2x^2-6x=0\)
\(\Leftrightarrow2x\left(x-3\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}2x=0\\x-3=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=3\end{matrix}\right.\)
b. Câu b bạn viết đề lại nhá!
d.\(\left(x-1\right)^2+x\left(5-x\right)=0\)
\(\Leftrightarrow x^2-2x+1+5x-x^2=0\)
\(\Leftrightarrow3x+1=0\)
\(\Leftrightarrow x=\dfrac{-1}{3}\)
e.
\(\left(2x-3\right)\left(2x+3\right)-\left(x+5\right)^2-3\left(x-1\right)\left(x+2\right)=0\)
\(\Leftrightarrow4x^2-9-x^2-10x-25-3x^2-3x+6=0\)
\(\Leftrightarrow-13x-28=0\)
\(\Leftrightarrow x=\dfrac{-28}{13}\)
a. \(x^2-7x+6=0\)
\(\Leftrightarrow x^2-6x-x+6=0\)
\(\Leftrightarrow\left(x^2-6x\right)-\left(x-6\right)=0\)
\(\Leftrightarrow x\left(x-6\right)-\left(x-6\right)=0\)
\(\Leftrightarrow\left(x-6\right)\left(x-1\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=1\\x=6\end{matrix}\right.\)
