Answer:
Y1 intercept = 2
(0,2) (3,-7)
m= (-7 - 2) / (3-0) =-9/3 = - 3
Then y = - 3x + 2
Y2 intercept = - 8
(0,-8) (3,-7)
m = (-7 - - 8) / (3-0) = 1/3
Then y= (1/3)x-8
To find the final term to compete the square you need to divide the 'x' term by 2 then square it

- equivalent equation
84/4=21
now take the 2 even numbers below 21 and the 2 even numbers above 21
18 +20 + 22 +24 = 84
the numbers are 18, 20, 22 & 24