What is the third side of 5 and 7 phyagorean theorem

Which of the following transformations does not preserve congruence? * 5 points a. (x, y) → (y − 3, x − 3) b. (x, y) → (x + 5, y − 1) c. (x, y) → (y + 9, −x + 2) d. (x, y) → (3x + 1, 3y − 2)

Can someone me with this problem i don't understand i need

If f(x)=-x^2+6x-1 and g(x)=3x^2-4x-1,find(f+g)(x)