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You need to build a pen for your dog…

September29

‘Sadie’ is such a lovely dog – playful, cuddly and, well, just cute! But, your parents are going out to buy 24 meters of fencing to make a pen for dear Sadie. What will you do while they are out shopping? Why, play with Sadie of course? No, no, no – you have to put your math skills to use and work out the maximum size that Sadie’s pen can be made using the 24 meters of fencing. But, being the helpful parents they are, they have suggested that you use an Excel spreadsheet to find out the maximum area using different lengths and widths for the pen. A snapshot of the spreadsheet is set up for you and one attached for you to complete. The solution will be posted in the ‘Post Support’ shortly, or you can comment back to this post. Good luck!

Area of Dog Pen-1cs7z3a

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Post Support

NCEA Level 2 Algebra Problem. Using the information given, the shaded area = 9, that is:
y(y-8) = 9 –> y.y – 8y – 9 =0
–> (y-9)(y+1) = 0, therefore y = 9 (can’t have a distance of – 1 for the other solution for y)
Using the top and bottom of the rectangle,
x = (y-8)(y+2) = (9-8)(9+2) = 11
but, the left side = (x-4) = 11-4 = 7, but rhs = y+? = 9+?, which is greater than the value of the opp. side??
[I think that the left had side was a mistake and should have read (x+4)?]

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