Question

A) 2+4+6+......100
B) 5+10+15+....500
C) Daca x=6 și y+z = 11, atunci calculați x*y + x*y
D) 7+8+9+....+35
Repede vă rog .

Answer 1

$a. 2(1+2+3+...+50)=2 *50*51 :2=50*51=2250$
$b. 5(1+2+3+...+100)=5*100*101:2=5*50*101=25250$
$d. 1+2+...+7+8+9+...35-(1+2+3+4+5+6)=$
$=35*36:2 -(6*7:2)=630-21=609$