Question

2021-2020+2019-2018+...+5-4+3-2+1
ajutor

Answer 1

Explicație pas cu pas:

2021 - 2020 + 2019 - 2018 + ............. + 3 - 2+ 1 = ...

1. +. 1. +............... + 1. + 1 = .....

2021 - 1 = 2020 numere

2020 : 2 = 1010 grupe de câte 1

1010 • 1 + 1 = 1011

Answer 2

$\bf 2021-2020+2019-2018+...+5-4+3-2+1 =$

$\bf \underbrace{(2021 -2020 )+(2019 - 2018)+.....+(5 - 4)+(3 - 2) }_{1010 \: grupe} + 1 =$

$\bf \underbrace{1+1+.....+1+1 }_{1010 \: ori} + 1 = 1010 \cdot 1 + 1 =$

$\bf 1010 + 1 = \red{ \boxed{ \bf\: 1011 \: }}$

___________

$\bf \blue{Numarul \: grupelor }= [(2021 -2): 1 +1)]:2$

$\bf \blue{Numarul \: grupelor }= [(2019: 1 +1)]:2$

$\bf \blue{Numarul \: grupelor }= 2020:2 = \blue{1010}$