Question

Atividade 1) Encontre o valor numérico das expressões abaixo, para x = 3
Veja a resolução:
a) 5x + 7 =
5.3 + 7 =
15 + 7 = 22
5.3 cinco vezes três = 15
b) 6x + 8 =
c) 4x + 2 =
d) 8x + 5 =
e) 7x + 3 =

Answer 1

a)
5/6 + 1/2 x 3/4=

5 + 1 . 3 = 5 + 3 4.5 + 3.3
----- ---- ----- ------ ----- = ---------------
6 2 4 6 8 24

6,8: 2
3,4: 2
3,2: 2
3,1: 3
--------------
1,1 = 2.2.2.3 = 8.3 = 24

20 + 9 29
--------- = -----
24 24

*****************************
b)
5 - 7/4 x 1/2=

5 - 7 . 1 = 5 - 7 8.5 - 1.7
------ ---- ----- ----- = --------------
4 2 1 8 8

40 - 7 = 33
-------- ------
8 8

***********************************
c)
2/3 x 1/5 + 9/4=

2 . 1 + 9 2 + 9 4.2 + 15.9
---- ----- ----- = ------ ---- = -----------------
3 5 4 15 4 60

15,4: 2
15,2: 2
15,1: 3
5,1: 5
------------
1,1 = 2.2.3.5 = 4.15 = 60

8 + 135 143
------------ = -------
60 60

***********************************

d)
19/9 + 4/5 x 2 =

19 + 4 . 2
----- ----
9 5

9,5: 3
3,5: 3
1,5: 5
------------
1,1 = 3.3.5 = 9.5 = 45

19 + 8 5.19 + 9.8 95 + 72 167
----- ---- = ----------------- = ------------- = -------
9 5 45 45 45

********************************

e)
3/5 + 2/9 : 2/3=

3 + 2 . 3
----- ----- ----
5 9 2

3 + 3 (:3)
------ ----
5 9 (:3)

3 + 1 3.3 + 5.1 = 9 + 5 = 14
------ ---- = --------------- -------- -----
5 3 15 15 15


f)
2/7 x 3/5 - 1/8 : 5/6=

2 . 3 - 1 . 6
---- ---- ---- ----
7 5 8 5

6 - 6 (:2)
------ ------
35 40 (:2)

6 - 3 4.6 - 7.3 = 24 - 21 = 3
----- ------ = -------------- ------------ -----
35 20 140 140 140

35,20: 2
35,10: 2
35,5: 5
7,1: 7
----------
1,1 = 2.2.5.7 = 4.35 = 140

g)
3/4 + 5/9 : 1/6=

3 + 5 . 6
------ ----- ----
4 9 1

3 + 30 (:3)
----- -----
4 9 (:3)

3 + 10 3.3 + 4.10
----- ----- = ---------------
4 3 12

9 + 40 = 49
---------- -----
12 12


h)1/2 - 1/5 : 2

1 - 1 . 1 = 1 - 1 5 - 1 = 4 (:2) = 2
---- ----- ---- ------ ---- = --------- ---- ----
2 5 2 2 10 10 10 (:2) 5

Answer 2

Resposta:

a)22

b)36

c)14

d)29

e)24