Let f be the function given by f of x is equal to the square root of x plus 4 minus 3 over x minus 5, if x does not equal 5, and it's equal to c if x equals 5. And say if f is continuous at x equals 5, what is the value of c? So if we know that f is continuous at x equals 5, that means that the limit, the limit as x approaches 5 of f of x is equal to f of 5. This is the definition of continuity. And they tell us that f of 5, when x equals 5, the value of the function is equal to c. So this must be equal to c. So what we really need to do is figure out what the limit of f of x as x approaches 5 actually is. Now if we just try to substitute 5 into the expression right up here, in the numerator you have 5 plus 4 is 9, the square root of that is positive 3, the principal root is positive 3, 3 minus 3 is 0, so you get a 0 in the numerator, and then you get 5 minus 5 in the denominator, so you get 0 in the denominator. So you get this indeterminate form of 0 over 0.