7. $lim _{x→\infty }$ $\dfrac {5x-6} {3x^{4}+2x}$ 8. $l→^{m}\infty $ $\sqrt{\dfrac {4x+1} {5+2x}} $ 9. $lim _{x→-1}$ $\dfrac {6x+6} {2x^{2}-2}$ $10$ $lim _{x→2}\dfrac {3x^{2}-4x-4} {7x-14}$ $11$ $lim _{x→2}\dfrac {x^{4}-5x^{2}+4} {3x^{2}-6x}$ 12. $lim _{x→4}\dfrac {x^{2}-5x+4} {x^{2}+2x-24}$ $13.$ $x→\infty $ $\dfrac {3x^{4}+8x^{2}+6x^{3}} {12x^{3}+5x^{2}+4x^{5}}$ 14. $lim _{x→3}$ $\dfrac {x^{2}+7x-30} {x^{2-9}}$ 15. $l→\infty $ $\sqrt{\dfrac {40x^{4}+72x^{3}} {10x^{4}+2x}} $