19. [-/8 Points] DETAILS SCALC9 1.8.017. Use the definition of continuity and the properties of limits to show that the function is continuous on the given interval. f(x) = x+ Vx - 4, [4, 00) For a ? |4, we have lim f(x) _ lim x+ vx - 4 x - a x - a = lim (x) + lim by the sum law x - a x-a = lim (x) + lim by the root law x - a x- a = lim (x) + lim lim (4) by the difference law x - a X - x- a + 4 by the direct substitution property Therefore, fis continuous at x = a for every a in (4, ). Also, lim f(x) = = f(4), so f is continuous from the right at 4. Thus, f is continuous on [4, co). x-4+