Question

8) The perimeter of a rectangle is 20x2 + xy - 7y2 and one of it's sides is

7x2 - xy. Find the other side.

Answer 1

3x^2 + 3xy/2 - 7xy^2/2

Explanation:

So we know the perimeter is 20x^2 + xy - 7y^2,

To find any perimeter you need 2l + 2w = P so,

One of the sides is 7x^2 - xy

First plug in the values,

2(7x^2-xy) + 2w = 20x^2 + xy - 7y^2

Multiply,

14x^2-2xy + 2w = 20x^2 + xy - 7y^2

Subtract,

14x^2 - 2xy - 14x^2 + 2xy + 2w = 20x^2 + xy - 7y^2 - 14x^2 + 2xy

2w = 6x^2 + 3xy - 7y^2

w = 3x^2 + 3xy/2 - 7xy^2/2