Posted by Labz on Monday, June 4, 2012 at 8:40pm.
a) Determine an equation, in simplified form, for the family of cubic functions with zeros 2 + sqrt5 and 0.
b) Determine an equation for the member of the family with graph passing through point (2,20)

Math  Reiny, Monday, June 4, 2012 at 8:43pm
Since you have given me 4 distinct roots, the equation must be a quartic not a cubic
it would be
y = ax(x2)(x+√5)(x√5)
= ax(x2)(x^2  5)
to find a, sub in your given point (2,20) 
Math  Labz, Monday, June 4, 2012 at 8:51pm
thank you again!

Math  Steve, Tuesday, June 5, 2012 at 12:21am
If you mean roots of 0,2+√5 and 2√5, then then
y = x^3  4x^2  x