Question 762397
Area = length x width.
If you are have a uniform walkway, then you have to subtract that distance from both sides of the length and width.
{{{400 = (30-2X)*(20-2X)}}}
Use FOIL to simplify the right hand side of the equation.
*[invoke foil "(30-2X)(20-2X)"]
Rewrite the equation.
{{{400 = -100X + 4X^2 + 600}}}
Subtract 400 from both sides.
{{{0 = 4X^2 - 100X + 200}}}
Now use the quadratic equation to solve for X.
*[invoke quadratic "X", 4,-100,200]
X = 2.19 & 22.81
Now if you use 22.81 in the equation for the area of the garden you will come up with negative area. Since we can not have negative area 22.81 is not a real solution to this problem.
X = 2.19feet