Question

Determine a raiz de cada uma das funções abaixo:
a) y = 3x − 9
b) y = −2x + 7

Answer 1

A)

$y = 3x - 9\\0 = 3x - 9\\3x = 9\\x = 3$

B)

$\displaystyle y = -2x + 7\\0 = -2x + 7\\-2x = -7\\\\x = \frac{7}{2}$

C)

$y = 4x\\0 = 4x\\x = 0$

D)

$\displaystyle y = \frac{2x}{5} - \frac{1}{3}\\\\0 = \frac{2x}{5} - \frac{1}{3}\\\\0 = \frac{6x-5}{15}\\\\0 = 6x-5\\\\6x = 5\\\\x = \frac{5}{6}$

Answer 2

a) y = 3x - 9

3x - 9 = 0

3x = 0 + 9

3x = 9

x = 9/3

x = 3

b) y = -2x + 7

-2x + 7 = 0

-2x = 0 - 7

-2x = -7

(-2x = -7) * (-1)

2x = 7

x = 7/2

x = 3.5

c) y = 4x + 0

4x + 0 = 0

4x = 0

x = 0/4

x = 0

d) y = 2x/5 - 1/3

2x/5 - 1/3 = 0

2x/5 = 1/3

2x = 5/3

x = 5/6

x = 0.83