<PRE><B>Question 1145065</B>
&lt;br&gt;
What part of the problem do you need help with?&lt;br&gt;
You are given a formula for the height h as a function of time t:&lt;br&gt;
{{{h = 2+9t-5t^2}}}&lt;br&gt;
You are then given a height (4m) and asked to find the times t when the ball is that height:&lt;br&gt;
{{{4 = 2+9t-5t^2}}}&lt;br&gt;
That&#39;s a quadratic equation.  Put it in standard form and solve by your favorite method.&lt;br&gt;
{{{5t^2-9t+2 = 0}}}&lt;br&gt;
That one will factor....&lt;br&gt;
{{{(5t-1)(t-2) = 0}}}&lt;br&gt;
Can you finish?&lt;br&gt;
(If you weren&#39;t able to see that the quadratic was factorable, you can always solve any quadratic equation using the quadratic formula....)</PRE>