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a fost răspuns

aratati ca numarul a este patrat perfect:a) a=(1+2+3+...+99)×2+100 b) a=1+2+3+...+50-25×50 c) a=3+6+9+...+75-75

Răspuns :

Denispanait
a)a=([tex] \frac{99*100}{2} [/tex]) *2 + 100
a=99*100+100
a=10000
a=100*100=patrat perfect
b)a=[tex] \frac{50*51}{2} [/tex] - 25 * 50
a=25*51-25*50=25
a=5*5=patrat perfect
c)a=3(1+2+3+...+25)-75
a=3([tex] \frac{25*26}{2} [/tex]) - 75
a=3*25*13-75=975-75=900
a=30*30=patrat perfect

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