Plz !

what is the constant of variation for the quadratic variation?

a. 5

b. 10

c. 15

d. 25

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.

Heptagon is the correct ans