Question 1 )

limx->4 (7-3 x) = -5

I was able to solve it and found that d= -E/3 - But my problem is that how do I verify/show that my delta works? Please explain.

And there is another question where I am not sure how to approach it after simplifying it

Question 2)

lim x->2 (x^3)=8

|x-2||x^2+2x+4|<E |x-2|<d