Consider the elliptic-curve group defined by { (x,y) | x,y ∈ Z7 and x2 mod 7 = x3 + 2x +3 mod 7 } (ie, the group you get when a=2, b=3, and p=7). What is (2,1) + (2,1) in this group?

Consider the elliptic-curve group defined by { (x,y) | x,y ∈ Z₇ and x² mod 7 = x³ + 2x +3 mod 7 } (ie, the group you get when a=2, b=3, and p=7).

What is (2,1) + (2,1) in this group?

Write your answer as an ordered pair of integers with no spaces.