Question

preciso urgente se possivel abrir a imagem❗❗❗❗​

Answer 1

Explicação passo-a-passo:

5)

$\sf 5^{7x+8}=25$

$\sf 5^{7x+8}=5^2$

Igualando os expoentes:

$\sf 7x+8=2$

$\sf 7x=2-8$

$\sf 7x=-6$

$\sf x=\dfrac{-6}{7}$

Letra B

6)

a)

$\sf x^2-5x+6=0$

$\sf \Delta=(-5)^2-4\cdot1\cdot6$

$\sf \Delta=25-24$

$\sf \Delta=1$

$\sf x=\dfrac{-(-5)\pm\sqrt{1}}{2\cdot1}=\dfrac{5\pm1}{2}$

$\sf x'=\dfrac{5+1}{2}~\Rightarrow~x'=\dfrac{6}{2}~\Rightarrow~x'=3$

$\sf x"=\dfrac{5-1}{2}~\Rightarrow~x"=\dfrac{4}{2}~\Rightarrow~x"=2$

b)

$\sf 2x^2-4x+3=0$

$\sf \Delta=(-4)^2-4\cdot2\cdot3$

$\sf \Delta=16-24$

$\sf \Delta=-8$

Como $\sf \Delta < 0$, não há raízes reais

3)

$\sf |10x-30|=50$

• $\sf 10x-30=50$

$\sf 10x=50+30$

$\sf 10x=80$

$\sf x=\dfrac{80}{10}$

$\sf x=8$

• $\sf 10x-30=-50$

$\sf 10x=-50+30$

$\sf 10x=-20$

$\sf x=\dfrac{-20}{10}$

$\sf x=-2$

$\sf S=\{8,-2\}$

Letra A