How do you evaluate $sqrt(b^2-4ac)$ for a=2, b=-4, c=-6?

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Answer 1 · 2016-12-19T23:45:16

The discriminant $D=(-4)^2-4*2*(-6)$

$D=16-(-48)=16+48=64$ This is $>0$
so there will be two solutions to the equation $2x^2-4x-6=0$

The square root $sqrtD=sqrt64=8$

The two solutions being:

$x_(1,2)=(-b+-sqrtD)/(2a)=(+4+-8)/4=1+-2$

$->x=+3orx=-1$

How do you evaluate sqrt(b^2-4ac)sqrt(b^2-4ac) for a=2, b=-4, c=-6?