Area of rectangle = length × width
300 = (x+10) × x
300 = 10x + x^2
Now we have the equation y=x^2 + 10x - 300
We can factor this equation to get our zeroes, which are:
-5(1+sqrt(13)),
5(sqrt(13)-1)
We only use the positive zero because we can't have a negative dimension.
Your width would be:
5(sqrt(13)-1)
Your length would be:
5(sqrt(13)-1) + 10
