It is proved that the function f (x) = 1-1 / X is an increasing function on (-, 0)

It is proved that the function f (x) = 1-1 / X is an increasing function on (-, 0)


Let a and B be any two numbers on (-, 0), and a 〉 B
Then f (a) - f (b) = (1-1 / a) - (1-1 / b) = 1 / B-1 / A
=(a-b)/ab
0 > a > b, so A-B > 0, AB > 0
f(a)-f(b)>0
f(a) 〉f(b)
It's over