a)
\(\dfrac{2x-5}{x+5}\) =4 (ĐKXĐ : x ≠ -5)
⇔\(\dfrac{\left(2x-5\right)}{\left(x+5\right)}=\dfrac{4\left(x+5\right)}{\left(x+5\right)}\)
⇒(2x-5)=4(x+5)
⇔2x-5=4x+20
⇔2x-4x=20+5
⇔-2x=25
x=\(\dfrac{-25}{2}\)
Vậy pt có nghiệm x=\(\dfrac{-25}{2}\)
b)