\[\mathop {\lim }\limits_{x \to \infty } \sqrt {{b^2} - 4ac} \]
[tex]\mathop {\lim }\limits_{x \to \infty } \sqrt {{b^2} - 4ac} [/tex]
\mathop {\lim }\limits_{x \to \infty } \sqrt {{b^2} - 4ac} \
y=3x+x2+4−−−−−√
\[\mathop {\lim }\limits_{x \to \infty } \sqrt {{b^2} - 4ac} $
$sqrt {{b^2} - 4ac} $