Given the length of three sides of a triangle, which is a right triangle?

The isosceles triangle has two sides of equal length, a, that sre longer than the length of the base ,b. the equation 2a+b=15.7 can be used to find the sides length. if one of the longer sides is 6.3 centimeters what is the length of the base

For f(x) = 3x+1 and g(x) = x2 - 6, find (g/f)(x)

Can someone answer this question for me