.5=3.13x-4.905*(x^2)

Solution for .5=3.13x-4.905*(x^2) equation:

Simplifying
0.5 = 3.13x + -4.905(x2)

Solving
0.5 = 3.13x + -4.905x2

Solving for variable 'x'.

Reorder the terms:
0.5 + -3.13x + 4.905x2 = 3.13x + -3.13x + -4.905x2 + 4.905x2

Combine like terms: 3.13x + -3.13x = 0.00
0.5 + -3.13x + 4.905x2 = 0.00 + -4.905x2 + 4.905x2
0.5 + -3.13x + 4.905x2 = -4.905x2 + 4.905x2

Combine like terms: -4.905x2 + 4.905x2 = 0.000
0.5 + -3.13x + 4.905x2 = 0.000

Begin completing the square.  Divide all terms by
4.905 the coefficient of the squared term: 

Divide each side by '4.905'.
0.1019367992 + -0.6381243629x + x2 = 0

Move the constant term to the right:

Add '-0.1019367992' to each side of the equation.
0.1019367992 + -0.6381243629x + -0.1019367992 + x2 = 0 + -0.1019367992

Reorder the terms:
0.1019367992 + -0.1019367992 + -0.6381243629x + x2 = 0 + -0.1019367992

Combine like terms: 0.1019367992 + -0.1019367992 = 0.0000000000
0.0000000000 + -0.6381243629x + x2 = 0 + -0.1019367992
-0.6381243629x + x2 = 0 + -0.1019367992

Combine like terms: 0 + -0.1019367992 = -0.1019367992
-0.6381243629x + x2 = -0.1019367992

The x term is -0.6381243629x.  Take half its coefficient (-0.3190621815).
Square it (0.1018006757) and add it to both sides.

Add '0.1018006757' to each side of the equation.
-0.6381243629x + 0.1018006757 + x2 = -0.1019367992 + 0.1018006757

Reorder the terms:
0.1018006757 + -0.6381243629x + x2 = -0.1019367992 + 0.1018006757

Combine like terms: -0.1019367992 + 0.1018006757 = -0.0001361235
0.1018006757 + -0.6381243629x + x2 = -0.0001361235

Factor a perfect square on the left side:
(x + -0.3190621815)(x + -0.3190621815) = -0.0001361235

Can't calculate square root of the right side.

The solution to this equation could not be determined.