Answer:
The width of the walkway is 4 feet.
Step-by-step explanation:
The garden and a walkway around its perimeter have an area of 460 square feet.
The length of the garden = 15 feet
The width of the garden = 12 feet
Assuming that walkway is of uniform width, we can solve the following equation.
![(12+2x)\times(15+2x)= 460](https://tex.z-dn.net/?f=%2812%2B2x%29%5Ctimes%2815%2B2x%29%3D%20460)
Expanding this we get;
![4x^{2}+54x+180=460](https://tex.z-dn.net/?f=4x%5E%7B2%7D%2B54x%2B180%3D460)
![=> 4x^{2}+54x-280=0](https://tex.z-dn.net/?f=%3D%3E%204x%5E%7B2%7D%2B54x-280%3D0)
We will solve this using quadratic equation formula:
![x=\frac{-b\pm \sqrt{b^{2} -4ac} }{2a}](https://tex.z-dn.net/?f=x%3D%5Cfrac%7B-b%5Cpm%20%5Csqrt%7Bb%5E%7B2%7D%20-4ac%7D%20%7D%7B2a%7D)
Here a = 4 , b = 54 , c = -280
We get the roots as x = 4 and x = ![-\frac{35}{2}](https://tex.z-dn.net/?f=-%5Cfrac%7B35%7D%7B2%7D)
Neglecting the negative value, we will take x = 4 feet.
Hence, the width of the walkway is 4 feet.