[tex]zad.a\\\\x^{2} -9~~>~~0\\\\korzystam ~~ze~~wzoru~~skroconego~~mnozenia:\\x^{2} -y^{2} =(x-y)\cdot (x+y)\\\\x^{2} -3^{2} ~~>~~0\\\\(x-3)\cdot (x+3)>0\\x=3~~,~~x=-3 \\a=1~~\Rightarrow ~~a>0~~ramiona~~paraboli~~skierowane~~sa~~do~~gory\\\\x\in (-\infty , -3)\cup (3,+ \infty )\\\\\\zad,.b\\\\x^{2} +25=0 \\x\in \oslash ,~~brak ~~rozwiazan\\\\Podstawiajac ~~kazda~~liczbe~~rzeczywista~~podniesina~~do~~kwadratu\\wynikiem~~bedzie ~~liczba~~dodatnia,~~dodajac ~~do ~~niej~~25~~nigdy~~\\[/tex]
[tex]jej~~wynik~~nie~~bedzie~~rowny~~zeru.[/tex]
