Question

calcule os zeros das funções reais:
a) y: 4x -12
b) y: 2x +8
c) y: -x +5
d) y: -1\2x -10
e) y: 7 -21x

Answer 1

y = 0

a) y: 4x -12

0 = 4x - 12
12 = 4x
4x = 12
x = 12/4
x = 3

¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨
b) y: 2x +8

0 = 2x + 8
- 8 = 2x
2x = - 8
x = - 8/2
x = - 4

¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨
c) y: -x +¨5

0 = - x + 5
x = 5

¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨
d) y: -1\2x -10

0 = -   1    x   -   10
       -------
           2

10 = - x 
        ------
           2

10.2 = - x
20 = - x
- 20 = x
x = - 20

*************************
e) y: 7 - 21x

0 = 7 - 21x
21x = 7
x =  7   (:7)
     -----     
      21   (:7)

x =    1
        -----
          3

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