Răspuns:
(-1)¹×(-1)²×(-1)³...×(-1)²⁰⁰⁰ = 1
Explicație pas cu pas:
(-1)¹×(-1)²×(-1)³...×(-1)²⁰⁰⁰ = ?
(-1)¹×(-1)²×(-1)³...×(-1)²⁰⁰⁰ = (-1)ˣ
unde x = 1+2+3+4+.....+2000
x = (1+2000)·2000:2 = 2001·1000 = 2001000
Deoarece x = 2001000 = numar par =>
(-1) ^numar par = 1 =>
(-1)¹×(-1)²×(-1)³...×(-1)²⁰⁰⁰ = 1