lim_{x → 3}(x+\frac{x^2-9}{x-3})=lim_{x → 3}(x+(x+3))=3+(3+3)=9
2)
lim_{x → -4}(\frac{x^2-16}{x+4}-3x)=lim_{x →-4}((x-4)-3x)=(-4-4)-3\cdot (-4)=4
3)
lim_{x → -2}(\frac{4-x^2}{x-2}+x)=(\frac{4-(-2)^2}{-2-2}-2)=0-2=-2
4)
lim_{x → -3}(\frac{2x^2-18}{x+3}-2x)=lim_{x →-3}(2(x-3)-2x)=-6