Question 1143395
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NOTE: The "^" symbol (shift-6) is often used to denote exponents....<br>
{{{h(t) = -16t^2+60t+14}}}<br>
To find the time when the cannonball is 30 feet above the ground, set h(t)=30 and solve:<br>
{{{-16t^2+60t+14 = 30}}}
{{{-16t^2+60t-16 = 0}}}
{{{-4t^2+15t-4 = 0}}}<br>
It doesn't look like that's going to factor, so solve using the quadratic formula or a graphing calculator.<br>
Note that the cannonball starts below 30 feet, so there will be two times when it is at 30 feet -- one when it is rising and another when it is falling.