X tends to infinity, and the final result is 3, so X must cancel each other out, and x+ax=0.

a=- 1 b=3

The second question, again, is that x approaches infinity, so the final result must be that there is no X.

4x-()=- 1

It should be 4x+ 1 in brackets.

So ax? +bx+c=(4x+ 1)？ = 16x？ +8x+ 1

So a= 16, b=8, c= 1.