## anonymous one year ago A rectangular garden, 42 feet by 20 feet, is surrounded by a walkway of uniform width. If the total area of the garden and walkway is 1248 square feet, the width of the walkway is _____. [A] 2.5 ft [B] 3 ft [C] 2 ft [D] 3.29 ft

1. anonymous

Would I use the formula w= a/l?

2. jim_thompson5910

|dw:1433033340450:dw|

3. jim_thompson5910

|dw:1433033359239:dw|

4. jim_thompson5910

|dw:1433033378846:dw|

5. jim_thompson5910

|dw:1433033442595:dw|

6. anonymous

Oh ok

7. anonymous

And what would I do now?

8. anonymous

Do I add the 42 and the 2x?

9. jim_thompson5910

Area = Length * Width 1248 = (42+2x)*(20+2x) solve for x

10. anonymous

Um okay.. let me try 1248 = 840 + 4x

11. anonymous

?

12. anonymous

And then x would be 102?

13. jim_thompson5910

1248 = (42+2x)*(20+2x) 1248 = 840+124x+4x^2 ... FOIL 1248-1248 = 840+124x+4x^2 - 1248 4x^2 + 124x - 408 = 0

14. jim_thompson5910

use the quadratic formula to solve from here

15. anonymous

oh... I did that so wrong... lol

16. anonymous

I have never used the quadratic formula before...

17. jim_thompson5910

have you seen or heard of it before?

18. anonymous

No. not really..

19. jim_thompson5910

ok we can use a calculator instead if you want?

20. anonymous

kk

21. jim_thompson5910

ok wolfram alpha is a good calculator to use type in 4x^2 + 124x - 408 = 0 and hit enter and you'll get this link http://www.wolframalpha.com/input/?i=4x^2+%2B+124x+-+408+%3D+0

22. jim_thompson5910

the calculator will spit out x = -34 or x = 3 as the two solutions. x is some length, so it can't be negative so only x = 3 is the true solution

23. anonymous

Oh OK! Thank you, for coping with me

24. jim_thompson5910

you were fine, don't worry

25. jim_thompson5910