Question

(m+3)^2-(m-9)(m+9) при m= -1

Answer 1

(m+3)²-(m-9)(m+9)=m²+6m+9-(m²-9²)=m²+6m+9-m²+81=6m+90
подставляем m=-1
-6+90=84

Answer 2

m^2+6m+9-m^2+81=6m+9+81=6m+90
m= -1
-6+90= 84