Question

rezolvati exercițiile 1,2,3

Answer 1

1. 
A={x∈Z|-3≤x+3≤2}
-3≤x+3≤2 |-3
-6≤x≤-1
x∈{-6,-5,-4,-3,-2,-1}
S=-6-5-4-3-2-1=-21

2.
3x+2(4-3x)+11(x+12)>5(6x-7)-9(x+10)-8
3x+8-6x+11x+132>30x-35-9x-90-8
8x+140>21x-133
140+133>21x-8x
273>13x |:13
21>x
Raspuns: A

3.
9(4x-3)-7(3x+5)<5(3x+10)-4(2x+15)-4
36x-27-21x-35<15x+50-8x-60-4
15x-62<7x-14
15x-7x<-14+62
8x<48 |:8
x<6
x∈Z ⇒ x∈{1,2,3,4,5}
Raspuns: D

Answer 2

1. -3≤x+3≤2 |+(-3)-3-3≤x+3-3≤2-3
-6≤x≤-1x∈[-6,-1]
-6-5-4-3-2-1=-21  - suma
Nu corespunde nici o varianta de raspuns data

2. 3x+2(4-3x)+11(x+12) > 5(6x-7)-9(x+10)-8
3x+8-6x+11x+132 > 30x-35-9x-90-8
8x+140 > 21x-133
140+133 > 21x-8x
273 > 13x     | : 13
273/13 > 13x/13
21 > x
Raspuns corect :  A

3.  9(4x-3)-7(3x+5) < 5(3x+10)-4(2x+15)-4
36x-27-21x-35 < 15x+50-8x-60-4
15x-62 < 7x-14
15x-7x < -14+62
8x < 48   | : 8
8x/8 < 48/8
x < 6x∈Z   ⇒   x∈{1,2,3,4,5}
Raspuns corect :   D