Question

Найти предел функции:
$a) lim_{n to infty} frac{ 3n^{2}+3n-5 }{1- n^{2} } \ b) lim_{x to +-infty} frac{2+ 4x^{2}+ 3x^{3} }{ x^{3}-7x-10 } \ c) lim_{n to +-infty} frac{7 x^{2} +10x+20}{ x^{3}-10 x^{2} -1 }$