a.
\(\Leftrightarrow3x-x^2+x^2-4=11\)
\(\Leftrightarrow3x-4=11\)
\(\Leftrightarrow3x=15\)
\(\Leftrightarrow x=5\)
b.
\(\Leftrightarrow\left(x+5\right)^2-2\left(x+5\right)=0\)
\(\Leftrightarrow\left(x+5\right)\left(x+5-2\right)=0\)
\(\Leftrightarrow\left(x+5\right)\left(x+3\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x+5=0\\x+3=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=-5\\x=-3\end{matrix}\right.\)
\(a,x\left(3-x\right)+\left(x-2\right)\left(x+2\right)=11\\ 3x-x^2+x^2+1=11\\ 3x+1=11\Rightarrow x=\dfrac{11-1}{3}=\dfrac{10}{3}\)
\(b,2\left(x+5\right)=\left(x+5\right)^2\\ 2\left(x+5\right)-\left(x+5\right)\left(x+5\right)=0\\ \left(x+5\right)\left(2-x+5\right)=0\\ \left(x+5\right)\left(7-x\right)=0\)
=>x=-5 hoặc x=7
giúp mình với ạ, mình cần gấp lắm ạ
