Question

quais sao as raizes da equaçao x2-x-20=0?

Answer 1

$1+/- \frac{ \sqrt{81} }{2}$
$1+/- \frac{ \sqrt{1²-4.1.-20} }{2.1}$
$\frac{1+/-9}{2}$
x'=$\frac{1+9}{2}=5$
x"=$\frac{1-9}{2}=-4$
espero ter ajudado *-*

Answer 2

$x^{2} -x-20=0\\\\\\ a=1;b=-1;c=-20\\\\\\ \Delta=b ^{2} -4ac\to \Delta=(-1) ^{2} -4*1*(-20)\to \Delta=1 +80\to \Delta=81\\\\\\ x= \frac{-b+- \sqrt{\Delta} }{2a} \to \\\\ x= \frac{-(-1)+- \sqrt{81} }{2*1} \to\\\\ x= \frac{1+- 9} {2} \to \\\\\\ x'= \frac{1+ 9}{2} \to \\\\ x'= \frac{10}{2} \to \\\\x'=5\\\\\\ x''= \frac{1- 9}{2} \to \\\\x''= \frac{- 8}{2} \to\\\\ x''=-4\\\\ \\\\S=(-4;5)$





R.: As raízes dessa equação são -4 e 5.