对正数a、b、c、d、e, 有
(a + b + c + d)(b + c + d + e)(c + d + e + a) + (b + c + d + e)(c + d + e + a)(d + e + a + b) + (c + d + e + a)(d + e + a + b)(e + a + b + c) + (d + e + a + b)(e + a + b + c)(a + b + c + d) + (e + a + b + c)(a + b + c + d)(b + c + d + e)
≥8[(a + b)(b + c)(c + d) + (b + c)(c + d)(d + e) + (c + d)(d + e)(e + a) + (d + e)(e + a)(a + b) + (e + a)(a + b)(b + c)].
(a + b + c + d)(b + c + d + e)(c + d + e + a) + (b + c + d + e)(c + d + e + a)(d + e + a + b) + (c + d + e + a)(d + e + a + b)(e + a + b + c) + (d + e + a + b)(e + a + b + c)(a + b + c + d) + (e + a + b + c)(a + b + c + d)(b + c + d + e)
≥8[(a + b)(b + c)(c + d) + (b + c)(c + d)(d + e) + (c + d)(d + e)(e + a) + (d + e)(e + a)(a + b) + (e + a)(a + b)(b + c)].