# Math Help - Finding the cubic function rule

1. ## Finding the cubic function rule

Hi i would like some help on finding the expression for the following cubic curve:

hope someone can help

P.S

2. Originally Posted by Paymemoney
Hi i would like some help on finding the expression for the following cubic curve:

hope someone can help

P.S
1. The general equation of a cubic function is:

$f(x)=ax^3+bx^2+cx+d$

2. Since the graph passes through the origin you already know that d = 0.

3. Plug in the coordinates of the given points into the genral equation. You'll get a system of 3 equations:

$\left|\begin{array}{l}3 = 8a+4b+2c \\\frac34 = a+b+c \\ -3=-8a+4b-2c \end{array}\right.$

4. Solve for (a, b, c)

3. Thanks i think i know how to work it out now