Tolong bantu jawab no 3 sama 4 pake caranya lengkap *komposisi fungsi*

jawab 
3. 
a. fog(x)  = f { g(x)} = f (-x - 2) = 3(-x-2)² + 1
= 3(x² + 4x + 4 ) + 1
= 3x² +12x + 13

b. goh(-5) = g { h(-5)} = g {(1 +5 )/(-5+7)} = g (6/2)
= g(3) = -3 - 2  
= - 5

4. 
fog( 1/x - 1) = f { g(1/x -1)} = f(4 - (1/x  - 1))
= f (4 -1/x + 1)
= f (5 - 1/x)
= (5 - 1/x) - 1)/ (5 - 1/x) 
= (4 - 1/x) / (5 - 1/x)
= (4x - 1)/(5x -1)

b. gof(k) = 3 1/2 = 7/2
g { f(k)} = g ((k -1)/k) 
4 - (k - 1) /k  = 7/2
(4k - k +1)/k = 7/2
(3k + 1)/ k = 7/2
7k = 2(3k +1)
7k = 6k + 2
k = 2