Question

Exercitiile 2 , 4 , 6 si 9 . Am nevoie de ele pana maine ! Dau coroana ! *am nevoie in mod special de exercitiul 9 !!*

Answer 1

2)

2(x + 2) + 3x + 1

2x + 4 = 3x + 1

4 - 1 = 3x - 2x

x = 3

4)

25(2a + 3b) = 44(5a - b)

50a + 75b = 220a - 44b

75b + 44b = 220a - 50a

119b = 170a

a/b = 119/170

6)

21/(2x + 1)

x = 0 => 21/(0 + 1) = 21 /1 = 21

x = 1 => 21/(2 + 1) = 21/3 = 7

x = 2 => 21/5 ∉ N

x = 3 => 21/7 = 3

x = 4 => 21/9 ∉ N

x = 5 => 21/11 ∉ N

x = 6 => 21/13 ∉ N

x = 7 => 21/15 ∉ N

.......

x = 10 => 21/21 = 1

A = {1, 3, 7, 21}

9)

BOC + COD + AOD = 360 - AOB

(x + 15) + (x + 15) + 3x = 360 - 90

5x + 30 = 270

5x = 270 - 30

5x = 240

x = 48°

COD = 48° + 15° = 63°

AOD = 3×48° = 144°