Question

Cine stie plssss!
.........​

Answer 1

a) S1=1+2+3+....+45

S1=45×(45+1)/2

S1=45×46/2

S1=45×23

S1=1035

S2=1+2+3+....+69

S2=69(69+1)/2

S2=69×70/2

S2=69×35

S2=2415

b) S1=1+2+3+....+105

S1=105(105+1)/2

S1=105×106/2

S1=105×53

S1=5565

S2=1+2+3+....+125

S2=125(125+1)/2

S2=125×126/2

S2=125×63

S2=7875

Answer 2

Răspuns:

Explicație pas cu pas:

22.

x + 5 ≤ 17

x ≤ 12

A = {0; 1; 2; 3; 4; 5; 6; 7; 8; 9; 10; 11; 12}

_______

5 divide x + 3

x + 3 = 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15

B = {2; 7; 12}

__________________

A U B = {0; 1; 2; 3; 4; 5; 6; 7; 8; 9; 10; 11; 12}

A \ B = {0; 1; 3; 4; 5; 6; 8; 9; 10; 11}