A function rule is nothing more than a process that correlates changes in input to changes in output. If y is the output and x is the input, the function must be of the form y(x). Since "The output is four more than the input", the value of y is always 4 units greater than the value of x. The function rule is:
Yes, because when the side lengths of a triangle are in the ratio 3: 4: 5, then it is a right triangle. These sides are 6: 8: 10, then the triangle is a right one.
