Respuesta :

darealmarinda123

Answer:

-r^4+3r^3-21r+49

Step-by-step explanation:

(−r2+3r+−7)(r2+−7)

=(−r^2)(r^2)+(−r^2)(−7)+(3r)(r^2)+(3r)(−7)+(−7)(r^2)+(−7)(−7)

=−r4+7r2+3r3−21r−7r2+49

=−r4+3r3−21r+49