Salut! :)
a) ( - 1 ) × ( - 1 )² × ... × ( - 1 )²⁰ =
( - 1 )¹ + ² + ... + ²⁰ =
( - 1 )²⁰ × ²¹ : ² =
( - 1 )¹⁰ × ²¹ =
( - 1 )²¹⁰ = 1
b) ( - 1 ) + ( - 1 )² + ... + ( - 1 )²⁰ =
( - 1 + 1 ) + ( - 1 + 1 ) + ... + ( - 1 + 1 ) = 10 × 0 = 0
c) ( - 1 ) - ( - 1 )² - ... - ( - 1 )²⁰ =
- 1 + ( - 1 + 1 ) + ... + ( - 1 + 1 ) - 1 =
- 2 + 9 × 0 = - 2 + 0 = - 2
d) ( - 2 ) × ( - 2 )² × ... × ( - 2 )²⁰ : ( - 8 )⁷⁰ =
( - 2 )²¹⁰ : ( - 2³ )⁷⁰ =
( - 2 )²¹⁰ : ( - 2 )²¹⁰ = 1
