The velocity of a particle moving in the xy plane is given by = (5.6 t - 4.5 t2) + 8.2, with in meters per second and t (> 0) in seconds. (a) What is the acceleration when t = 3.3 s? (b) When (if ever) is the acceleration zero? (c) When (if ever) does the speed equal 10 m/s? I got the first 2 but when I went to find c I can't seem to get it. I took 10m/s = sqrt((5.6t - 4.5t^2)^2 + (8.2)^2 10^2 = (sqrt((5.6t - 4.5t^2)^2 + (8.2)^2)^2 100 = (5.6t - 4.5t^2)^2 + 67.24) 32.76 = (5.6t - 4.5t^2)^2 sqrt(32.76) = sqrt((5.6t - 4.5t^2)^2) 5.72 = 5.6t - 4.5t^2 0 = -4.5t^2 + 5.6t - 5.72 then I used quadratic to find out the two values... but I get a negative in the sqrt on the quadratic and I can't do that... any suggestions?