Question

$<var>x2-3x-4=0</var>$

Answer 1

$x^2-3x-4=0\\\Delta=(-3)^2-4.1(-4)\\\Delta=9+16\\\Delta=25$

$x= \frac{-b\pm\sqrt\Delta}{2a}$

$x= \frac{3\pm5}{2} \\ \\x_1= \frac{3+5}{2} \\x_1=4$

$x_2= \frac{3-5}{2} \\x_2=-1$

$S=\{4,-1\}$