document.write( "Question 48689: Maximizing profit. The total profit (in dollars) for sales of x rowing machines is given by p(x)= -0.2x^2+300x-200 . What is the profit if 500 are sold? For what value of x will the profit be at a maximum? \n" ); document.write( "
Algebra.Com's Answer #32223 by longjonsilver(2297)\"\" \"About 
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the differential gives you a turning point on a curve, either a max or a min (or a point of inflexion).\r
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\n" ); document.write( "\n" ); document.write( "p(x)= -0.2x^2+300x-200
\n" ); document.write( "p'(x)= -0.4x+300 where p'(x) is the differential
\n" ); document.write( "p'(x)= -0.4x+300 = 0
\n" ); document.write( "0.4x = 300
\n" ); document.write( "x = 300/0.4
\n" ); document.write( "x = 750\r
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\n" ); document.write( "\n" ); document.write( "p''(x) = -0.4 which is NEGATIVE. This is therefore a MAXIMUM point.\r
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\n" ); document.write( "\n" ); document.write( "So profit is maximised at x=750\r
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\n" ); document.write( "\n" ); document.write( "jon.
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