The harmonic mean of two numbers x and y, symbolized as h(x, y), is defined as 2 divided by the sum of the reciprocals of x and y, whereas the geometric mean g(x, y) is defined as the square root of the product of x and y (when this square root exists), and the arithmetic mean m(x, y) is defined as$${x+y}\over{2}$$ For which of the following pairs of values for x and y is g(x, y) equal to the arithmetic mean of h(x,y)and m(x, y)?
-
Ax =-2, y = -1
-
Bx = -1,y = 2
-
Cx = 2,y=8
-
Dx = 8, y=8
-
Ex = 8, y = 64
显示答案
正确答案: D