Question

Prove that \[a \lt b, c \lt d \implies a + c \lt b + d\] Prove that \[a \lt b, c \lt d \implies a + c \lt b + d\] @Mathematics

Answer 1

a<b, so a+c<b+c
c<d, so c+b<b+d
combime two equations together
so a+c<b+c<b+d
so a+c<b+d

Answer 2

works