a)

Wypiszmy te liczby:

-2, -1, 0, 1, 2

Suma:

$\underset{0}{\underbrace{\left(-2\right)+2}}+\underset{0}{\underbrace{1+\left(-1\right)}}+0=0$  

 

b)

Wypiszmy te liczby:

-6, -5, -4, -3, -2, -1, 0, 1, 2, 3, 4

Suma: 

$-6+\left(-5\right)+\underset{0}{\underbrace{\left(-4\right)+4}}+\underset{0}{\underbrace{\left(-3\right)+3}}+\underset{0}{\underbrace{\left(-2\right)+2}}+\underset{0}{\underbrace{\left(-1\right)+1}}+0=-11$  

 

c)

Wypiszmy te liczby:

-3, -2, -2, -1, 0, 1, 2, 3, 4, 5

Suma:

$5+4+\underset{0}{\underbrace{\left(-3\right)+3}}+\underset{0}{\underbrace{\left(-2\right)+2}}+\underset{0}{\underbrace{\left(-1\right)+1}}+0=9$  

 

d)

Suma:

$98+\underset{0}{\underbrace{\left(-97\right)+97}}+\underset{0}{\underbrace{\left(-96\right)+96}}+\underset{0}{\underbrace{\left(-95\right)+95}}+\dots \underset{0}{\underbrace{\left(-2\right)+2}}+\underset{0}{\underbrace{\left(-1\right)+1}}+0=98$