1) You know that , and you know that from corner to corner the length is 130 feet. You need to use pythagorean theory to solve this one. The hypotenuse is 130, and the other sides are W, and W + 70.
This gives us:
Now we simply have to solve for W. First multiply out the last term:
Note that is equal to . Now, bring everything to one side:
Now just use the quadratic equation to find W.
2) The square root function is only defined for numbers greater than or equal to 0. Therefore:
Now just solve the inequality for x:
We now have that must be equal to or less than 6 for the function to be defined.