(a) 2x^2+3 + 4x^3+1=4x^3+2x^2+4 (simply add the definitions of the two separate functions)
(b) -4x^3+2x^2+2
(c) multiply: (2x^2+3)(4x^3+1)=8x^5+12x^3+2x^2+3
(d) divide: (2x^2+3)/(4x^3+1) has a domain that excludes 4x^3+1=0, 4x^3=-1 so x=-cuberoot of (1/4) is excluded from the domain. All other real values of x are permitted.
The domains of (a) - (c) put no constraints on x, so the domain is the real numbers.
(e) put x=3 in (a): 4*27+2*9+4=130
(f) put x=4 in (b): -4*64+2*16+2=-222
(g) put x=2 in (c): 8*32+12*8+2*4+3=363
(h) put x=1 in (d): 5/5=1