Question

tìm x biết x+\(\dfrac{2}{7}\)=\(\dfrac{-49}{x+2^2}\)

Answer 1

\(x+\dfrac{2}{7}=\dfrac{-49}{x+2^2}\)

\(⇔x+\dfrac{2}{7}+\dfrac{49}{x+4}=0\)

\(⇔\dfrac{7x(x+4)+14(x+4)+343}{7(x+4)}=0\)

\(⇔\dfrac{7x^2+28x+14x+48+343}{7(x+4)}=0\)

\(⇔\dfrac{7x^2+42x+391}{7(x+4)}=0\)

\(⇔7x^2+42x+391=0\)

\(⇔x∉R\)