dy/dx=25, 35, 45, 55
d2y/dx2=10,10,10 (this constant just proves that it is a quadratic relation)
Now we can set up a system of equations for ax^2+bx+c
16a+4b+c=80, 9a+3b+c=45, 4a+2b+c=20 getting differences
7a+b=35, 5a+b=25 and again
2a=10, a=5, making 7a+b=35 become:
7(5)+b-35, b=0, making 4a+2b+c=20 become:
4(5)+2(0)+c=20, c=0 so
y=5x^2
So the constant of variation for this quadratic is 5.
