Question

(exercitiul 1) Calculati suma : S=11+22+33+... + 22154.


(exercitiul 2) Stiinda ca XY+YZ=320 si X+Z=16 , aflati Y.
(exercitiul 3)Daca X+Y=10 si A+B=11, calculati S= AX+A(ori) Y+ B (ori) X +B (ori) Y

Answer 1

1.
S=11+22+33+... + 22154= 11*(1+2+3...+2014)= 11*2014*2015/2=22320155

2.
xy+yz=320
x+z=16

xy+yz=y*(x+z)=320 ⇒
16*y=320
y=320/16
y=20

3.
x+y=10
A+B=11

Ax+Ay+Bx+By= A(x+y)+B(x+y) = (x+y)* (A+B)=10*11=110