Question

x2 – 3x – 4 = 0 (é x ao quadrado, menos três x, menos quatro​

Answer 1

$x^{2} - 3x -4 = 0\\\\a=1\\b=-3\\c=-4\\\\x=\frac{-b\pm\sqrt{\Delta} }{2a}\\\\\Delta =b^{2} -4.a.c\\\Delta=(-3)^{2} -4.1.-4\\\Delta=9+16\\\Delta=25\\\\x=\frac{-b\pm\sqrt{\Delta} }{2a} \\\\x=\frac{3\pm5}{2.1} \\\\x=\frac{3\pm5}{2} \\\\x'=3+5.2=\frac{8}{2} = 4\\x''=3-5.2=-\frac{2}{2} =-1 \\\\S =\{-1,4 \}$