Question

Answer 1

a: ĐKXĐ: \(x\notin\left\{-3;1\right\}\)

b: \(P=\dfrac{3x^2+5x-4-x^2+1-x^2-6x-9}{\left(x-1\right)\left(x+3\right)}\)

\(=\dfrac{x^2-x-6}{\left(x-1\right)\left(x+3\right)}\)

c: Để P=-1/2 thì \(\dfrac{x^2-x-6}{\left(x-1\right)\left(x+3\right)}=\dfrac{-1}{2}\)

\(\Leftrightarrow2x^2-2x-12=-\left(x^2+2x-3\right)=-x^2-2x+3\)

\(\Leftrightarrow3x^2=15\)

\(\Leftrightarrow x^2=5\)

hay \(x=\pm\sqrt{5}\)