Question

simplificaţi fracţia F(x)=X²-10X+21 
                                             X²-9

Answer 1

$x^{2} -10x+21= x^{2} -3x-7x+21=x(x-3)-7(x-3)=$(x-7)(x-3)
$x^{2} -9=(x+3)(x-3)$

$\frac{(x-7)(x-3)}{(x+3)(x-3)}= \frac{x-7}{x+3}$