Question 797050
{{{ h=-4.9t^2+8t+1.5 }}}
If the form of the equation is
{{{ f(x) = ax^2 + bx + c }}}, then the x-coordinate of 
the maximum or minimum is at {{{ x[max] = -b/(2a) }}}
In your problem,
{{{ a = -4.9 }}}
{{{ b = 8 }}}
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{{{ t[max] = -8/(2*(-4.9)) }}}
{{{ t[max] = 8/9.8 }}}
{{{ t[max] = .8163 }}}
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Now find {{{ h[max] }}}
{{{ h[max] =-4.9*.8163^2+8*.8163+1.5 }}}
{{{ h[max] = -4.9*.6663 + 6.5304 + 1.5 }}}
{{{ h[max] = -3.2651 + 8.0304 }}}
{{{ h[max] = 4.765 }}}
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Here's the plot:
 {{{ graph( 400, 400, -3, 3, -6, 6, -4.9x^2 + 8x + 1.5 ) }}}