Question

ALGUEM AJUUUUJJ. AJUDA

Answer 1

Resposta:

a)

3-x<5+3x

-2 < 4x

x>-1/2

b)

x²-9≤ 0

(x-3)*(x+3) ≤ 0

++++(-3)------(3)++++

 

x ∈ [-3 ,3]

c)

1-x-2x² ≥ 0

2x²+x-1 ≤ 0

x'=[-1 +√(1+8)]/4 =(-1+3)/4=1/2

x''=[-1 -√(1+8)]/4 =(-1-3)/4=-1

++++++(-1)------(1/2)+++++++++

x ∈ [-1/2 ,1/2]

d)

x/(x-3)<4

x/(x-3)-4 <0  

(x-4x-12)/(x-3) < 0

(-3x-12)/(x-3) < 0

(-3)*(x+4)/(x-3) < 0

(x+4)/(x-3) >0

p=x+4  ..raiz=-4

p-----------------(-4)++++++++++++++++

q=x-3  ..raiz=3

q-----------------(3)+++++++++++++++++

Estudo de sinais:

p--------(-4)+++++++++++++++++++++++++

q-----------------(3)+++++++++++++++++

p/q++++++(-4)-----(3)+++++++++++++++++

x ∈ (-∞,-4)U(3,+∞)