Answer:
20m
Step-by-step explanation:
(m+5)^2-(m-5)^2
FOIL
(m+5) (m+5)
m^2 +5m+5m+25
m^2 +10m +25
FOIL
(m-5) (m-5)
m^2 -5m-5m+25
m^2 -10m +25
Replace into the original equation
m^2 +10m +25 - (m^2 -10m +25)
Distribute the minus sign
m^2 +10m +25 - m^2 +10m -25
Combine like terms
20m
