Question

Solve the equation 4*e+2=1 (mod5)

Answer 1

Here's a way to do it.

Let 4e +2 = 5n +1 . . . . . . for some integer n

Then e = (5n -1)/4 = n + (n -1)/4

We want (n-1)/4 to be an integer, so let it be integer m.

... m = (n -1)/4

... 4m = n -1

... 4m +1 = n

Substituting this into our expression for e gives

... e = (5(4m+1) -1)/4 = (20m +4)/4 = 5m +1

e = 5m+1 for any integer m