Is this relation a function?(8,2)(-4,1)(-6,2)(8,9)

Plzzz maths ! quadratic sequences=an^2+c 1) 11,17,27,41,59 2) 7,16,31,52,79 3) 6,18,38,66,102 4) 0,9,24,45,72 5) 0,12,32,60,96

Write two subtraction equations that are equivalent to 5 + 12 = 17.

Find the slope of a line given the following two points