Question

calculati urmatoarea suma: 3+5+6+10+9+15+...+45+75

Answer 1

Răspuns:

191.

Explicație pas cu pas:

3+5+6+10+

3(3+5+6+15)+

75 =

(3+5+6+15)(1+3) + 75 =

29x4 + 75 =

116 + 75 =

191.

Answer 2

3+5+6+10+9+15+...+45+75 =

=(3+6+9+12+…..+45)+(5+10+15+20+….+75)

=3(1+2+3+….+15)+5(1+2+3+…+15)

=(3+5)(15•16/2)

=8•120

=960