Question

URGENTEEEEEEEEEEEEE PORRRR FAVORRRRR
Estude a variação de sinal das seguintes funções:
a) y = 7x – 4

e) y = -2x + 6

f) y = -3x - 7

g) y = x – 5

h) y = -9x + 1

Answer 1

Explicação passo-a-passo:

a) $\sf y=7x-4$

$\sf 7x-4=0$

$\sf 7x=4$

$\sf x=\dfrac{4}{7}$

Temos que:

=> $\sf y > 0,~para~x > \dfrac{7}{4}$

=> $\sf y < 0,~para~x < \dfrac{7}{4}$

=> $\sf y=0,~para~x=\dfrac{7}{4}$

e) $\sf y=-2x+6$

$\sf -2x+6=0$

$\sf 2x=6$

$\sf x=\dfrac{6}{2}$

$\sf x=3$

Temos que:

=> $\sf y > 0,~para~x < 3$

=> $\sf y < 0,~para~x > 3$

=> $\sf y=0,~para~x=3$

f) $\sf y=-3x-7$

$\sf -3x-7=0$

$\sf 3x=-7$

$\sf x=\dfrac{-7}{3}$

Temos que:

=> $\sf y > 0,~para~x < \dfrac{-7}{3}$

=> $\sf y < 0,~para~x > \dfrac{-7}{3}$

=> $\sf y=0,~para~x=\dfrac{-7}{3}$

g) $\sf y=x-5$

$\sf x-5=0$

$\sf x=5$

Temos que:

=> $\sf y > 0,~para~x > 5$

=> $\sf y < 0,~para~x < 5$

=> $\sf y=0,~para~x=5$

f) $\sf y=-9x+1$

$\sf -9x+1=0$

$\sf 9x=1$

$\sf x=\dfrac{1}{9}$

Temos que:

=> $\sf y > 0,~para~x < \dfrac{1}{9}$

=> $\sf y < 0,~para~x > \dfrac{1}{9}$

=> $\sf y=0,~para~x=\dfrac{1}{9}$