Question

degree 3 polynomial. It goes through the point (5,−2.1). Find the polynomial.

Answer 1

You are given f(x)=ax^3+bx^2+cx+d and f(5)=-2.1 .
I don't think that is enough info to find all the constants there...
Maybe it just wants to find a polynomial satisfying the above info
... so maybe you could just look at f(x)=ax^3+1 or f(x)=x^3+d etc...