Question 636051
  <pre><font face = "Tohoma" size = 3 color = "indigo"><b> 
Hi,
ax^2 +bx + c = 0
x^2-2x+10=0       {{{x = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}}
discriminant
{{{ sqrt( b^2-4*a*c )}}}
{{{ sqrt( 4-4*1*10 )}}}
{{{ sqrt( -36 )}}}
{{{ sqrt( (-1)-36 )}}}     ||   i^2 = -1
{{{ sqrt( (i^2)-36)}}} = ± 6i ,  NO real solutions, Note: parabola will NOT cross x-axis
{{{drawing(300,300,   -6, 6, -6, 20,   grid(1),
graph( 300, 300, -6, 6, -6, 20,0,x^2-2x+10 ))}}}

Simplify: 
{{{(7+2i)/(4+i)}}}   || multiplying both numerator and denominator by conjugate (4-i).  Note:  i^2 = -1 
{{{ ((7 + 2i)(4-i))/((4+i)(4-i)) = (28 + i + 2)/ 17 = (30 + i)/17}}}