SOLUTION: The length of a rectangle is 5 inches more than 4 times the width. If the area of the rectangle is 84 square inches, find the length and the width.

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Question 1166865: The length of a rectangle is
5
inches more than
4
times the width. If the area of the rectangle is
84
square inches, find the length and the width.
Found 2 solutions by josgarithmetic, greenestamps:
Answer by josgarithmetic(39613) About Me  (Show Source):
You can put this solution on YOUR website!
width w
length 4w+5
Area, w%284w%2B5%29=84

4w%5E2%2B5w-84=0
.
.
%28w-4%29%284w%2B21%29=0

highlight%28w=4%29-----------width
4w%2B5=highlight%2821%29---------length

Answer by greenestamps(13195) About Me  (Show Source):
You can put this solution on YOUR website!


The solution using formal algebra is good practice in the use of algebra for a beginning student.

If a formal algebraic solution is not required, the work required to get an answer is MUCH less if you solve the problem by trial and error.

Look at pairs of numbers whose product is 84 and find the one which satisfies the condition that one of the numbers is 5 more than 4 times the other.

84*1 no...
42*2 no...
28*3 no...
21*4 YES

ANSWER: the rectangle is 21x4 inches