document.write( "Question 882158: Please help me solve this word problem: A ball is thrown into the air and follows a path modeled by the function h(t)= -5(t-1.4)^2 +10, where time, t, is in seconds and height h(t) is in meters. Determine when the ball will hit the ground. \n" ); document.write( "

Algebra.Com's Answer #532730 by KMST(5328) $\"\"$ $\"About$

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$\"h%28t%29=+-5%28t-1.4%29%5E2+%2B10\"$ is the height of the ball above the ground $\"t\"$ seconds after it is thrown.
\n" ); document.write( " $\"h%28t%29=0\"$ means the ball is 0 meters above the ground, meaning that it is on the ground.
\n" ); document.write( "The equation making $\"h%28t%29=0\"$ gives you 2 answers for $\"t\"$ , one negative and one positive.
\n" ); document.write( "The negative answer makes no sense, because we only care about the time after the ball was thrown.
\n" ); document.write( "(We do not know or care where the ball was for the \"negative\" values of $\"t\"$ that represent before the throw. Maybe it was in someone's pocket before being thrown, but we do not care).
\n" ); document.write( "
\n" ); document.write( " $\"system%28h%28t%29=+-5%28t-1.4%29%5E2+%2B10%2Ch%28t%29=0%29\"$ ---> $\"-5%28t-1.4%29%5E2+%2B10=0\"$ ---> $\"10=5%28t-1.4%29%5E2\"$ ---> $\"10%2F5=%28t-1.4%29%5E2\"$ ---> $\"2=%28t-1.4%29%5E2\"$
\n" ); document.write( "From $\"%28t-1.4%29%5E2=2\"$ we get the two answers:
\n" ); document.write( " $\"%28t-1.4%29%5E2=2\"$ ---> $\"system%28t-1.4=sqrt%282%29%2C%22or%22%2Ct-1.4=sqrt%282%29%29\"$ ---> $\"system%28t=sqrt%282%29%2B1.4%2C%22or%22%2Ct=-sqrt%282%29%2B1.4%29\"$
\n" ); document.write( " $\"highlight%28t=sqrt%282%29%2B1.4=about2.8%29\"$ is the answer you want.
\n" ); document.write( "The ball hits the ground $\"highlight%28about2.8%29\"$ seconds after being thrown. \n" ); document.write( "

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