Answer:
The dimensions are 4.5 ft by 10 ft.
Explanation:
The formula for the area of a quadrilateral is A= lw (area = the length multiplied by the width). We are given the area of 45 sq. ft so A = 45.
Now we know that l is double (twice - two times!) the width plus another foot. That means that l = 2w+1. We can use the substitution rule to replace l with 2w+1. So we have 45=(2w+1)w. From here you can distribute the w and you should get 45=2w2+1w. From here you should be able to solve for w by factoring, and therefore also solve for l.
45 factors into 5 and 9, and we know that 2x5=10, and 10-9=1 so that looks like a good bet! The only other factors for 45 would be 1 and 45, and that isn't going to give us 1w, so it must be 5 and 9.
So now let's solve it:
2w2 + w = 45
2w2 + w - 45 = 0
(2w -9) (w+5) = 0
2w - 9 = 0
w + 5 = 0
So w = 9/2 or w = -5
We can't have a negative width, so the answer is 9/2! Which means our length of 2w+1 = 10.
So the dimensions are 4.5 ft by 10 ft. Hope this helps you.