Răspuns :

Dianageorgiana794id

Răspuns:

x=1+3+5+...+225

x=( 1+2+3+4+5+...+224+225)-(2+4+6+....+224)

x= 225·226:2 - 2·(1+2+3+...+112)

x=225·113-2·112·113:2

x=225·113-112·113

x=113·(225-112)

x=113·113=113² → patrat perfect

ElenaMunteanu01id

Răspuns: x = 12796

Explicație pas cu pas:

In suma avem: (225 - 1) : 2 + 1 = 224 : 2 + 1 = 113 termeni

[tex]x = 1 + 3 + 5 + .......+225[/tex]

[tex]x = (1 + 225) \cdot 113 : 2[/tex]

[tex]x = 226\cdot 113 : 2[/tex]

[tex]x = 113\cdot 113[/tex]

[tex]\boxed{x = 12769}[/tex]

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