1) lim [ ( x^2+2x-15)/(x^2-9)] , x->3 . 2) lim { [ 2z]/ [ 4 + z )^1/2 - ( 4-z)^1/2]} , z->0. 3) lim{[2-x^1/2]/[3-(2x+1)1/2]},x->4. 4) lim{[x+27]/[(x)^1/3+3]}, x-> -27