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1 ) Efectuati urmatoarele operarii 

a) 11,1 + 22,2 +33,3 +.............+99,9 

b)11,11 +22,22 +33,33 +.......................+99,99

AJUTATI-MA VA ROG !
MERSI MULT !!!!









Răspuns :

Se calculeaza pe rand.
La primul punct:
11,1+22,2+33,3+44,4+55,5+66,6+77,7+88.8+99.9=33.3+77.7+122.1+166.5+99.9=111+288.6+99.9=399.6+99.9=499.5
La al doilea se procedeaza exact la fel.
11.11+22.22+33.33+44.44+55.55+66.66+77.77+88.88+99.99=33.33+77.77+122.21+166.65+99.99=111.1+288.86+99.99=399.96+99.9=499.95
Eu preferam sa lucrez cu ,, darea in factor comun ... " , adica:
a)11,1+22,2+33,3+...+99,9 = 11,1 (1+2+3+...+9) = 
=[tex]11,1\cdot\frac{9\cdot10}{2}=11,1\cdot45=499,5[/tex]
b=11,11+22,22+33,33+...+99,99=
=[tex]11,11\cdot(1+2+3+...+9)\;=\;11,11\cdot\frac{9\cdot10}{2}=11,11\cdot45=499,95 [/tex]