Question 196502
x^2 - 5x + 7 = 0 
the quadratic formula
{{{x = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}}
In this equation: a=1; b=-5; c=7
{{{x = (-(-5) +- sqrt(-5^2 - 4 * 1 * 7 ))/(2*1) }}}
:
{{{x = (5 +- sqrt(25 - 28 ))/(2) }}}
:
{{{x = (5 +- sqrt(-3))/(2) }}}
extract the square root of -1
{{{x = (5 +- i*sqrt(3))/(2) }}}
You can write this:
{{{x = 5/2 + (sqrt(3)i)/2 }}}
and
{{{x = 5/2 - (sqrt(3)i)/2 }}}