Question 208682
First off we need to get this equation into standard form which is ax^2+bx+c=0.  To do that we need to add 20x and 12 to both sides.<br>

4x^2+20x+12=0.  Now we can plug into the quadratic formula.  
{{{x = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}}<br>

where a = 4, b = 20, and c = 12.  Plugging in you get:
{{{x = (-20 +- sqrt( 20^2-4*4*12 ))/(2*4) }}}<br>

Now we simplify:
{{{x = (-20 +- sqrt( 20^2-4*4*12 ))/(2*4) }}}
{{{x = (-20 +- sqrt( 400-192 ))/(8) }}}
{{{x = (-20 +- sqrt( 208 ))/(8) }}}<br>

208 is divisible by 16 so you can take divide by 16 and then pull a 4 out because the square root of 16 is 4. 

So the expression above simplifies down to<br>

{{{x = (-20 +- 4*sqrt( 13 ))/(8) }}}<br>

Since there is a factor of 4 present in all 3 whole numbers we can divide everything by 4.  Doing so will result in:<br>

{{{x = (-5 +- sqrt(13))/(2) }}}<br>

And that is your final exact answer.