22/05/26 15:14:39 PV2MRVLr.net
a + b - 2√ab = (√a - √b)²≧0 ∴ a+b ≧ 2√ab
c + d - 2√cd = (√c - √d)²≧0 ∴ c+d ≧ 2√cd
2√ab + 2√cd - 4√√abcd = (2√ab - 2√cd)²≧0 ∴ 2√ab + 2√cd ≧ 4√√abcd
∴ a+b+c+d ≧ 4√√abcd
22/05/26 15:14:39 PV2MRVLr.net
a + b - 2√ab = (√a - √b)²≧0 ∴ a+b ≧ 2√ab
c + d - 2√cd = (√c - √d)²≧0 ∴ c+d ≧ 2√cd
2√ab + 2√cd - 4√√abcd = (2√ab - 2√cd)²≧0 ∴ 2√ab + 2√cd ≧ 4√√abcd
∴ a+b+c+d ≧ 4√√abcd