Question 411026
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Hi
As important as correctly using the quadratic formula is starting with the
correct quadratic equation to apply it to:
-x^2+6x-21=0    |Must multiply ALL terms by -1 to proceed in tha fashion
 x^2 - 6x + 21 = 0
{{{x = (6 +- sqrt( -48 ))/(2) }}}
{{{x = (6 +- sqrt( -16*3 ))/(2) }}}
{{{x = (6 +- 4i*sqrt( 3 ))/(2) }}}
{{{x = (3 +- 2i*sqrt( 3 )) }}}

x^2+6x-21=0   |If... this were the correct quadratic (using as an example)
-6+-sqrt(120)/(2)
-6+-sqrt(4*30)/(2)
-6+-2sqrt(30)/(2)
-3+-sqrt(30)   |important to take the 'sqrt(4)out front'