Solve t^2-t=3(7+t)
Expand RHS: t2 - t = 21+ 3tCollect all terms on one side: t2 - 4t - 21 = 0Factorise and solve by inspection / use the quadratic formula to solve for t: (t + 3)(t - 7) = 0 / t = [ -(-4) ± ( (-4)2 - 4x(1)x(-21) )1/2 ] / 2(1)t = -3, t = 7
