Question

the area of rectangular plot of land fenced all round is 2000 sq. yards and the total length of fencing 180 yards. find the length and width of plot.

Answer 1

Let l = length
Let w = width

It was said that the total length of fencing is 180 yards. Note that perimeter of rectangle is equal to:
P = 2l + 2w

Substituting,
180 = 2l + 2w
90 = l + w
We can have an expression for length in terms of the width:
l = 90 - w

Recall that area of rectangle is length times the width. Substituting,
A = l * w
2000 = (90 - w) * w
2000 = 90w - w^2
w^2 - 90w + 2000 = 0

This is a quadratic equation, and it is immediately factorable. You'll have two roots for w, but choose only the positive, since dimensions cannot be negative. Finally, solve for the length.
Hope this helps~ `u`

Answer 2

x=-40,x=-50