Question 74153
{{{(t^2-t)/2=15}}}Start with the given equation
{{{(1/2)t^2-(1/2)t=15}}}Rewrite the equation
{{{(1/2)t^2-(1/2)t-15=0}}}Get all terms to one side. Now we can solve for t by using the quadratic formula
*[invoke quadratic "t", .5, -.5, -15 ]
So t=-5 and t=6