word problem ?

[sw87]

I keep getting really big numbers and no answer I get is close to one of the multiple choices
Q:
A rectangle with an area of 80cm^2 has a width that is three more then one half its length. What is the width of the rectangle?


80cm^2=L(1/2L+3)
80cm^2=1/2L^2+3L
(80cm^2=1/2L^2+3L)2 to get rid of the fraction
160cm^2=L2+6L now I'm stuck

 

[Denis]

I keep getting really big numbers and no answer I get is close to one of the multiple choices Q:
A rectangle with an area of 80cm^2 has a width that is three more then one half its length. What is the width of the rectangle?
80cm^2=L(1/2L+3)
80cm^2=1/2L^2+3L
(80cm^2=1/2L^2+3L)2 to get rid of the fraction
160cm^2=L2+6L now I'm stuck

DO NOT include stuff like "cm^2" in equations :shock:
You have (which is correct):
L^2 + 6L = 160
So:
L^2 + 6L - 160 = 0
Solve for L by factoring or using quadratic equation.

 

[sw87]

thank you very much I understand now i factor then set each equal to zero then solve for L. i come up with 10 as my solution because you can't have negative side of a rectangle.

 

[Deleted member 4993]

thank you very much I understand now i factor then set each equal to zero then solve for L. i come up with 10 as my solution because you can't have negative side of a rectangle.

Correct

L[sup:ss4ammph]2[/sup:ss4ammph] + 6L - 160 = 0

(L + 16)(L - 10) = 0 ? L = 10