Problem 51 of 7
Find when projectile h(t)=-4.9t^2+19.6t reaches the ground.
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solve quadratic for height zero and select valid time.
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Ground height is h=0 and valid time must be nonnegative in context.
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Solution
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1. Set h(t)=0.
2. Solve the resulting quadratic.
3. Keep nonnegative time values and interpret launch versus landing.
Use the worked steps, then substitute the final answer back into the original relationship to confirm it satisfies the prompt.
Negative-time roots as physical landing times.