If you factor your area equation, you get area=(x+18)(x-5). Since area=l*w, you know that one side of your rectangle has to be x+18 units long, and the other has to be x-5 units long. since perimeter=2l+2w, it can be said that your perimeter expression is 2(x+18)+2(x-5)
this can be simplified as follows:
perimeter=2[(x+18)+(x-5)]
perimeter=2(x+18+x-5)
perimeter=2(2x+13)
perimeter=4x+26
Grade: 9
Level: Highschool
Subject: Math
Topic: Factoring trinomials
Solving "Rectangular Area" word problem with a quadratic equation ... MathWOEs
Two worked-out examples showing how writing and solving a quadratic equation (by factoring) can help solve a word problem dealing with rectangular area.
Using a Quadratic to find the Dimensions of a Rectangle
In this video we use a quadratic equation to find the dimensions of a rectangle that has the given properties. It involves identifying relationships and substitution to get the equation in terms of one variable then solving for that variable.
Check out my website,http://www.drphilsmathvideos.com, it has all my videos plus some online lessons you can try!
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