document.write( "Question 242593: A rectangular storage bin is to be made from a rectangular piece of sheet metal
\n" ); document.write( "12 cm by 10 cm, by cutting out equal corners of side x and bending up the
\n" ); document.write( "sides. Find x if the storage bin is to hold 90cm³(volume).\r
\n" ); document.write( "\n" ); document.write( "- I thought it might be x(120 - 4x²)= 90cm³
\n" ); document.write( "which I guess would be 4x³ - 120x + 90 = 0 but I'm not sure where to go from here, or even if I'm heading in the right direction.
\n" ); document.write( "thanks heaps
\n" ); document.write( "manda \n" ); document.write( "
Algebra.Com's Answer #177888 by ankor@dixie-net.com(22740)\"\" \"About 
You can put this solution on YOUR website!
A rectangular storage bin is to be made from a rectangular piece of sheet metal
\n" ); document.write( "12 cm by 10 cm, by cutting out equal corners of side x and bending up the
\n" ); document.write( "sides.
\n" ); document.write( "Find x if the storage bin is to hold 90cm³(volume).
\n" ); document.write( ":
\n" ); document.write( "We know that the length and width will be decreased by 2x and height will = x
\n" ); document.write( ":
\n" ); document.write( "The volume, L * W * H:
\n" ); document.write( "(12-2x)(10-2x)* x = 90
\n" ); document.write( "(120 - 24x - 20x + 4x^2) * x = 90
\n" ); document.write( "which is:
\n" ); document.write( "x(4x^2 - 44x + 120) = 90
\n" ); document.write( ":
\n" ); document.write( "4x^3 - 44x^2 + 120x - 90 = 0
\n" ); document.write( ":
\n" ); document.write( "It's difficult to solve this for x, not being an integer solution
\n" ); document.write( ":
\n" ); document.write( "Using the graphing calc y = 4x^3 - 44x^2 + 120x - 90 = 0
\n" ); document.write( ":
\n" ); document.write( "\"+graph%28+300%2C+200%2C+-2%2C+5%2C+-10%2C+10%2C+4x%5E3+-+44x%5E2+%2B+120x+-+90+%29+\"
\n" ); document.write( ":
\n" ); document.write( "Two solutions: x = 1.28cm and x = 2.39cm, either value for x will give 90 cu/cm \n" ); document.write( "
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