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Demonstreaza ca numarul a este patrat perfect,unde a=1+2+3+...+100+51x101


Răspuns :

[tex]a=1+2+3+...+100+51*101= \\ ~~ = \frac{100*101}{2}+51*101= \\ ~~=50*101+51*101= \\ ~~=101(50+51)= \\ ~~=101*101= \\ ~~=101^2 ~-patrat~perfect. [/tex]
1+2+3.....100+51x101
100x(100+1):2+51x101
100x101:2+51x101
50x101+51x101=
101x(51+51)=
101x101=101²
101² este patrat perfect