Question 65770
A quadratic equation is one in which the highest power of the independent variable (x in this case) is 2.  Quadratic comes from the latin "Quadra" meanining square.

Solve by completing the square:
{{{2x*2 +10x + 11 = 0}}} First,divide through by 2 in order to get the coefficient of {{{x^2}}} = 1.
{{{x^2 + 5x + 11/2 = 0}}} Next, subtract 11/2 from both sides.
{{{x^2 + 5x = -11/2}}} Now add to both sides, the square of half the coefficient of x. This is:{{{(5/2)^2 = 25/4}}}
{{{x^2 + 5x + 25/4 = (25/4)-11/2}}} Now simplify this.
{{{(x+5/2)^2 = 3/4}}}  Take the square root of both sides.
{{{x+5/2 = sqrt(3/4)}}} The {{{sqrt(3/4)}}} will have a + or - in front of it. Subtract {{{5/2}}} from both sides.
{{{x = (-5/2)+-sqrt(3/4)}}}

The solutions are:
{{{x = (-5+sqrt(3))/2}}} = -1.63397 (Approx.)
{{{x = (-5-sqrt(3))/2}}} = -3.36603 (Approx.)