Question 736049
The depth of the submarine after M minutes is given by {{{ d(m) = -7500 + 80m }}}
The limitations here are that {{{ d(m) }}} starts out at {{{ d(0) = -7500 }}} m and
rises, but , since it's a submarine, it can't go any higher than {{{ d(m) = 0 }}}. That
would put it above the water's surface.
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Also the equation is set up for {{{ d(0) = -7500 + 80*0 }}}. Since the minutes can't
be less that {{{ m = 0 }}}, {{{ -7500 }}} is the lowest depth that the equation can habndle
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Now I can chart these 2 positions, {{{ d(m) = -7500 }}}, and {{{ d(m) = 0 }}}
(1)
 {{{ d(m) = -7500 }}} meters
 {{{ d(0) = -7500 + 80*0 }}} 
{{{ m = 0 }}} minutes
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(2)
{{{ d(m) = 0 }}} meters
{{{ 0 = -7500 + 80m }}}
{{{ 80m = 7500 }}}
{{{ m = 93.75 }}} minutes
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So, the range is {{{ -7500 }}} to {{{ 0 }}} meters
The domain is {{{ 0 }}} to {{{ 93.75 }}} minutes
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Here's the plot:
{{{ graph( 400, 400, -20, 120, -8000, 200, 80x - 7500 ) }}}