Respuesta :

Answer:

r^2-18r+81

Step-by-step explanation:

rxr=r^2

rx-9=-9r

-9xr=-9r

-9x-9=81

-9r-9r=-18r

Answer:

r^2-18r+81

Step-by-step explanation:

r × r = r^2

r × -9 = -9r

-9 × r = -9r

-9 × -9 = 81

->

r^2-18r+81

Hope that helps! :)