Math Is Fun Forum

lovethegto

Member

Registered: 2010-10-29

Posts: 11

Geometry question

I have no idea how to do this problem can someone help?
Susan wants to plant a rectangular garden in her yard, the width of the garden will be 9ft less than its length, and she wants it to have an area of 52ftsq . find the length and width of the garden?  please help.

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Geometry question

Hi lovethegto;

Call the length x, so the width is x - 9. Area = L *W = x(x-9) = 52.

We have the quadratic:

Factoring we get.

So x = 13 and x = -4.

We drop x = -4 so we are left with x = 13 therefore Length = 13 ft. and Width = 4 ft.

Welcome to the forum!

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In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

lovethegto

Member

Registered: 2010-10-29

Posts: 11

Re: Geometry question

Hey thanks for your help... i wonder if my teacher gave us the wrong problem because we are not up to factoring yet:)

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Geometry question

Have you had the quadratic formula? You could solve it with that.
Or you could graph it and use interval bisection and solve it that way.
Or you could produce a simple iteration:

Or you could use the rational root theorem, which says if the poly has rational roots they must be an element of

Now as a student it is hard for me to believe that you would be familiar with any of the above methods and not had factoring.
But I have seen students who undertood the quadratic formula and did not know how to factor.
If your math knowledge was self taught then it is quite possible that you would be familiar with one of those methods and not know how to factor.

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In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.