Question

1- determine o delta:
a) x ao quadrado - x - 20 = 0

Answer 1

$x^{2} -x-20=0\\\\\\ a=1;b=-1;=-20\\\\\\ \Delta=b^2-4ac\to \\\\ \Delta=(-1)^2-4*1*(-20)\to \\\\ \Delta=1+80\to \\\\ \Delta=81$