Question

exx 5-6 va roggg e pentru test nush nimic dau coroana mersii

Answer 1

Răspuns:

Explicație pas cu pas:

5) -5 <= 2x -9 <= 5

4 <= 2x <= 14 |:2

2 <= x <= 7

A = [2, 7]  interval

-14 < 3x -5 < 4

-9 < 3x < 9 |:3

-3 < x < 3

B = (-3, 3)

AUB = (-3, 7),  A∩B = [2, 3)

6) 1/2*3 = 1/2 -1/3

1/3*4 = 1/3 -1/4

..........

1/29*30 = 1/29 -1/30

a = 1/2 -1/3 +1/3 -1/4 + 1/4 -1/5 +...+1/29 -1/30 =

1/2 -1/30 = (15 -1)/30 = 14/30 = 7/15

0,(3)= 1/3

1/3 < 7/15 < 1/2  sau

10 < 14 < 15  (num.comun =30)