please solve asap

Object Height. Suppose an object is thrown straight up from the ground. The height after t seconds is given by the formula h(t) = -5+ + 86t2 + 221 (a) The time in seconds when the object reached the highest point was Note: Round to 4 digits after the decimal point, if rounding is required O 25.8 s O O s 8.6 s O 221 s O 11.4667 s None of the other answers (b) The height is maximized at the critical point x = a because the second derivative test found Of" ( a ) 0 Of' (a ) = 0 O f (a) was positive to the left of x = a and negative to the right Of" (a ) = 0