SOLUTION: Please help me solve this..... The width of a rectangle is 6 meters less than its length. The area is 315 square meters. Find the length of the rectangle.

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Question 689435: Please help me solve this..... The width of a rectangle is 6 meters less than its length. The area is 315 square meters. Find the length of the rectangle.
Answer by MathLover1(20849) About Me  (Show Source):
You can put this solution on YOUR website!

given:
The width W of a rectangle is 6m less than its length L.
W=L-6m
The area A is 315m%5E2.
to find: the length L

as you know A=L%2AW.......plug in given values

315m%5E2=L%2A%28L-6m%29
315m%5E2=L%5E2-L6m%29
L%5E2-L6m-315m%5E2=0%29.....use quadratic formula to solve for L

L+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
L+=+%28-%28-6m%29+%2B-+sqrt%28+%28-6m%29%5E2-4%2A1%2A%28-315m%5E2%29+%29%29%2F%282%2A1%29+
L+=+%286m+%2B-+sqrt%28+36m%5E2%2B1260m%5E2+%29%29%2F2+
L+=+%286m+%2B-+sqrt%28+1296m%5E2+%29%29%2F2+

L+=+%286m+%2B-+36m+%29%2F2+.........find only positive root because the length cannot be negative

L+=+%286m+%2B+36m+%29%2F2+
L+=+42m+%2F2+
highlight%28L+=+21m+%29+.....your answer
we can find the width too:
W=L-6m
W=21m-6m
highlight%28W=15m%29