a: Khi x=3 thì \(A=\dfrac{3+3}{9-4}=\dfrac{6}{5}\)
b: \(B=\dfrac{x^2-x-2-x^2+2x}{\left(x+2\right)\left(x-2\right)}=\dfrac{x-2}{\left(x+2\right)\left(x-2\right)}=\dfrac{1}{x+2}\)
c: \(P=\dfrac{B}{A}=\dfrac{1}{x+2}:\dfrac{x+3}{x^2-4}=\dfrac{x-2}{x+3}\)
Để P<1 thì P-1<0
=>(x-2-x-3)/(x+3)<0
=>x+3>0
=>x>-3