Question

DAU 20 DE PUNCTE PLUS COROANA
imi trebuie doar raspunsurile​

Answer 1

Răspuns:

Explicație pas cu pas:

c) S₁ = 4¹⁵ - 3·4¹⁴ - 3·4¹³ - .... 3·4 = 4¹⁵ - 3·(4¹⁴+4¹³+....+4) = 4¹⁵ - 3·a

a = 4¹⁴+4¹³+....+4 I·4 => 4a = 4¹⁵+4¹⁴+...+4² =>

4a = 4¹⁵+a-4 => 3a = 4¹⁵-4 =>

S₁ = 4¹⁵ -4¹⁵+4 = 4

d) S₂ = 5¹⁰⁰-4·5⁹⁹-4·5⁹⁸-....-4·5 = 5¹⁰⁰-4·(5⁹⁹+5⁹⁸+...+5) = 5¹⁰⁰-4·b

b = 5⁹⁹+5⁹⁸+...+5  I·5 => 5b = 5¹⁰⁰+5⁹⁹+...+5² =>

5b = 5¹⁰⁰+b-5 => 4b = 5¹⁰⁰-5 =>

S₂ = 5¹⁰⁰-5¹⁰⁰+5 = 5

a) (-5-10-15-....-400) : (-1-2-3-...-80) =

= (-5)·(1+2+3+....+80) : [(-1)(1+2+3+...+80) =

= (-5):(-1) = 5