-x^2+6x-4 g(1/2)

Simplify the following:
-(1/2)^2+6/2-4

(1/2)^2 = 1^2/2^2:
-1^2/2^2+6/2-4

1^2 = 1:
-1/2^2+6/2-4

2^2 = 4:
-1/4+6/2-4

6/2 = (2×3)/2 = 3:
-1/4+3-4

Put -1/4+3-4 over the common denominator 4. -1/4+3-4  =  -1/4+(4×3)/4+(4 (-4))/4:
-1/4+(4×3)/4+(4 (-4))/4

4×3  =  12:
-1/4+12/4+(4 (-4))/4

4 (-4)  =  -16:
-1/4+12/4+-16/4

-1/4+12/4-(16)/4  =  (-1+12-16)/4:
(-1+12-16)/4

-1+12-16 = 12-(1+16):
12-(1+16)/4

1+16 = 17:
(12-17)/4

12-17  =  -(17-12):
-(17-12)/4

| 1 | 7
- | 1 | 2
| 0 | 5:
Answer: | 
| (-5)/4

Your heading and your question are different.  So I do not know what you want.