a. A(1,5) apartne graficului => f(1)=5
f(1)=5
4*1+b=5
b=1
b. f(x)=4x+4
x=0 => f(0)=4 => A(0,4)
f(x)=0 =>4x+4=0 =>x=-1 => B(-1,0)
c. f(x)<=f(3)
4x+1<=4*3+1
4x<=12
x<=3
x apartine (-infinit, 3]
d. f0f(1)=21
f(f(1))=21
f(4+b)=21
4(4+b)+b=21
16+4b+b=21
5b=5
b=1
f. f(x)=y =>4x+3=y
f(2x)=-y=> 8x+3=-y
8x+3=-4x-3
12x=-6
x=-6/12=-1/2
y=-1/2*4+3=1
