9а²/а²-25-9/а+5 При а=корень 23 ПОМОГИТЕ ПОЖАЛУЙСТА!!!

[latex]\frac{9a^2}{a^2-25}-\frac9{a+5}=\frac{9a^2}{(a-5)(a+5)}-\frac9{a+5}=\frac{9a^2-9(a-5)}{(a-5)(a+5)}=\frac{9a^2-9a+45}{(a-5)(a+5)}=\\=\frac{9(a^2-a+5)}{a^2-25}\\ \frac{9(a^2-a+5)}{a^2-25}=\frac{9((\sqrt{23})^2-\sqrt{23}+5)}{(\sqrt{23})^2-25}=\frac{9(23-\sqrt{23}+5)}{23-25}=\frac{9(28-\sqrt{23})}{-2}=-\frac{9(28-\sqrt{23})}{2}[/latex]