Question

Answer 1

\(B=\dfrac{x^2-x+1+4}{x^2-x+1}\)

\(=1+\dfrac{4}{x^2-x+1}=1+\dfrac{4}{x^2-x+\dfrac{1}{4}+\dfrac{3}{4}}\)

\(=1+\dfrac{4}{\left(x-\dfrac{1}{2}\right)^2+\dfrac{3}{4}}< =1+4:\dfrac{3}{4}=1+\dfrac{16}{3}=\dfrac{19}{3}\)

Dấu = xảy ra khi x=1/2