Respuesta :

Answer:

19. Option A

20. Option B

Step-by-step explanation:

Answer of 19 is A by using the a^2 - b^2 = ( a - b) ( a + b) so this will be (r-1 )( r+1) because we have r^2 so we have to factorize it


Answer of 20 is B by following the same steps