document.write( "Question 632571: I have a piece of cardboard, twice as long as it is wide. I will cut 4x4 squares out of each corner, so i fold up the corners and use it as a tray. The volume of the tray will be 96 cubic inches. How large is the piece of cardboard? \n" ); document.write( "
Algebra.Com's Answer #398466 by ankor@dixie-net.com(22740)![]() ![]() You can put this solution on YOUR website! I have a piece of cardboard, twice as long as it is wide. \n" ); document.write( " I will cut 4x4 squares out of each corner, so i fold up the corners and \n" ); document.write( " use it as a tray. \n" ); document.write( "The volume of the tray will be 96 cubic inches. \n" ); document.write( "How large is the piece of cardboard? \n" ); document.write( ": \n" ); document.write( "let x = the width of the cardboard \n" ); document.write( "then \n" ); document.write( "2x = the length of the cardboard \n" ); document.write( ": \n" ); document.write( "The dimensions of the tray \n" ); document.write( "the 4\" squares will reduce both dimensions of the cardboard by 8\" \n" ); document.write( ": \n" ); document.write( "(x-8) = the width of the tray \n" ); document.write( "(2x-8) = the length of the tray \n" ); document.write( "4 inches = the height of the tray \n" ); document.write( ": \n" ); document.write( "The volume of the tray, Length * Width * height = 96 cu/in \n" ); document.write( "(2x-8)*(x-8)*4 = 96 \n" ); document.write( "FOIL \n" ); document.write( "4(2x^2 - 16x - 8x + 64) = 96 \n" ); document.write( "4(2x^2 - 24x + 64) = 96 \n" ); document.write( "8x^2 - 96x + 256 = 96 \n" ); document.write( "A quadratic equation \n" ); document.write( "8x^2 - 96x + 256 - 96 = 0 \n" ); document.write( "8x^2 - 96x + 160 = 0 \n" ); document.write( "simplify, divide by 8 \n" ); document.write( "x^2 - 12x + 20 = 0 \n" ); document.write( "Factors to \n" ); document.write( "(x-2)(x-10) = 0 \n" ); document.write( "Two solutions but only one will make sense \n" ); document.write( "x = 10 inches is the width \n" ); document.write( "then \n" ); document.write( "20 inches is the length \n" ); document.write( ": \n" ); document.write( "The original cardboard is 20 by 10 \n" ); document.write( ": \n" ); document.write( ": \n" ); document.write( "Check this by finding the volume \n" ); document.write( "(20-8)*(10-8)*4 = 96 \n" ); document.write( " |