Question

(a+9) . (X-9) =
(M-1) . (M+1) =
(3x+5). (3x-5) =
(2-7x) . (3+7x)=

Answer 1

$(a+9)(x-9)=\\ax-9a+9x-81\\\\(m-1)(m+1)=\\m^2+m-m-1=\\m^2-1\\\\(3x+5)(3x-5)=\\9x^2-15x+15x-25=\\9x^2-25\\\\(2-7x)(3+7x)=\\6+14x-21x-49x^2=\\-49x^2-7x+6$



Espero ter ajudado.
Bons estudos! :)

Answer 2

(a+9)(9-x)
ax-9a+9x-9x9
ax-9a+9x-81

(M-1)(m+1)
M^2-1^2
M^2-1

(3x+5)(3x-5)
(3x)^2-5
8x^2-5^2
9^2x-25

Espero te ajudado :)