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ALGEBRA WORD PROBLEM
Kieryn T. asked • 01/10/18
The length of a rectangle is 5 cm more than twice the width. The perimeter of the rectangle is 34 cm. Find the dimensions of the rectangle.
I am having trouble with this problem. I asked my parents and they didnt know what to do. I am stuck and i have looked through my notes and nothing has helped.
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Mikaila D. answered • 01/10/18
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The dimensions of the rectangle are two unknowns: The length "l" and the width "w"
The perimeter of a rectangle is found as P = 2*l + 2*w
We also know that the length is 5cm more than twice the width. l = 2*w + 5
These two equations gives us a system of linear equations.
P = 2*l + 2*w
l = 2*w + 5
We can use substitution to replace the "l" in the first equation with 2*w + 5
P = 2*(2*w + 5) + 2*w
P = 4*w + 10 + 2*w
P = 6*w + 10
We know that P = 34cm
34 = 6*w + 10
Subtract 10 from both sides
24 = 6 * w
Divide both sides by 6
4 = w
Now that we know the width, we can find the length by substituting 4 for "w" in the second equation.
l = 2*4 + 5
l = 8 + 5
l = 13