document.write( "Question 288390: what is the length and width of a rectangle if the perimeter is 24m and the area is 35m2? \n" ); document.write( "
Algebra.Com's Answer #209037 by jaydducote(11)![]() ![]() You can put this solution on YOUR website! Area=length times width, or A=LW \n" ); document.write( "Perimeter=2W+2L \n" ); document.write( "We know the perimeter is 24m, so 24=2W+2L \n" ); document.write( "We know the area is 35 square meters, so 35=LW \n" ); document.write( "Now you need to do substitution to solve. You have to solve for either L or W in terms of the other variable. I would solve the first one for W: \n" ); document.write( "24=2W+2L \n" ); document.write( "subtract 2L from both sides \n" ); document.write( "24-2L=2W \n" ); document.write( "now divide both sides by 2 \n" ); document.write( "12-L=W \n" ); document.write( "so we know that W=12-L. Substitute that into the other equation: \n" ); document.write( "35=LW \n" ); document.write( "35=L(12-L) \n" ); document.write( "distribute the L \n" ); document.write( "35=12L-L^2 \n" ); document.write( "This now looks tricky, there is a square term, so we will need to factor \n" ); document.write( "Move everything to the left side \n" ); document.write( "L^2-12L+35=0 \n" ); document.write( "Now, think about which two numbers add to twelve and multiply to get 35. Think of the factors of 35. Only 7 times 5 works, which happen to add to 12! \n" ); document.write( "Since we have a -12L but a +35, and we know we are adding to get to 12, not subtracting, we should conclude that both the 7 and 5 must be negative. Factored, we get this: \n" ); document.write( "(L-5)(L-7)=0 \n" ); document.write( "This means that our two \"zeros\" or solutions are the numbers that make this statement true. If L is 5 or 7, the entire value is 0, so those are our answers. W=5, L=7. \n" ); document.write( " |