document.write( "Question 1061644: This is an optimization problem.\r
\n" );
document.write( "\n" );
document.write( "The problem states that a cylinder has a volume of 1000 cubic inches; therefore, what dimensions will minimize the surface area?
\n" );
document.write( "The conflict is that the answer I have doesn't match the teacher's answer.
\n" );
document.write( "Here's what I did:\r
\n" );
document.write( "\n" );
document.write( "V = (pi) * (r^2) * h
\n" );
document.write( "1000 = (pi) * (r^2) * h
\n" );
document.write( "1000 / ((pi) * (r^2)) = h\r
\n" );
document.write( "\n" );
document.write( "SA = 2 * ( (pi) * r^2 ) + (2 * (pi) * r * h)
\n" );
document.write( "SA = 2 * ( (pi) * r^2 + (pi) * r * ( 1000 / ((pi) * (r^2)) )
\n" );
document.write( "SA = 2 * ( (pi) * r^2 + 1000/r )
\n" );
document.write( "SA = 2 * (pi) * r^2 + 2000/r\r
\n" );
document.write( "\n" );
document.write( "SA' = 4 * (pi) * r - 2000/(r^2)
\n" );
document.write( "0 = 4 * (pi) * r - 2000/(r^2)
\n" );
document.write( "4 * (pi) * r = 2000/(r^2)
\n" );
document.write( "4 * (pi) * r^3 = 2000
\n" );
document.write( "r^3 = 500 / (pi)
\n" );
document.write( "r = root3 ( 500 / (pi) )\r
\n" );
document.write( "\n" );
document.write( "The problem is that r is supposed to be equal to root3 ( 250 / (p) ).
\n" );
document.write( "Where did I go wrong? \n" );
document.write( "
Algebra.Com's Answer #676407 by solver91311(24713)![]() ![]() You can put this solution on YOUR website! \r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "You did not go wrong. The radius that gives the minimum total surface area is \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "John \n" ); document.write( " \n" ); document.write( "My calculator said it, I believe it, that settles it \n" ); document.write( " ![]() \n" ); document.write( " |