Răspuns:
Explicație pas cu pas:
a. 3x≤-12 5x<-7
x≤-4 x<[tex]\frac{-7}{5}[/tex]
x∈(-∞,-4]
b. x²+11x-12<0
Δ=121+48=169
[tex]x_{1}=\frac{-11+13}{2} =1\\\\x_{2}=\frac{-11-13}{2} =-12[/tex]
x |-∞ -12 1 +∞
x²+11x-12 |+ + + + +0 - - - - - - 0 + + + + + +
x∈(-12,1)
7x-3≤6x-9
x≤-6
x∈(-∞,-6]
Sf= x∈(-12,-6]
