text: can you help me please? 1. a ball is thrown into the air straight up so that its height is represented by the equation h(t)=-5t^2 (negative 5t squared)+15t. at what time t in seconds, other than 0, does the ball hit the ground? 2.find all values of k such that the equation 3x^2 (3x squared)-2x+k=0 has imaginary roots. 1.  h must be zero  0=-5t^2+15t 0=t(-5t+15) t=0 or  -5t+15=0 5t=15 t=15/5=3  answer: 3 seconds   2. 3x^k-2x+k=0 delta must be less than zero  4-4(3 . k)<0 4 < 12k  4/12<k  1/3 < k