Posted by **Emma** on Friday, January 20, 2012 at 11:22pm.

How do I find zeros on a graph of a cubic function? I can tell that two of the zeros are -4 and 3 because they show on the graph, but how do I find the other?

- Pre-Calc B -
**Anonymous**, Saturday, January 21, 2012 at 1:16am
y = a x ^ 3 + b x ^ 2 + c x + d = a ( x - x1 ) ( x - x2 ) ( x - x3)

y = a [ x - ( - 4 ) ] ( x - 3 ) ( x - x3 )

y = a ( x + 4 ) ( x - 3 ) ( x - x3 )

You must know 4 points on graph to solve this equation.

Maybe your function has a double root (that is, one of the zeroes has a multiplicity of two).

In this case :

y = a ( x + 4 ) ( x + 4 ) ( x - 3 )

OR

y = a ( x + 4 ) ( x - 3 ) ( x - 3 )

## Answer this Question

## Related Questions

- Math Problem (please help) - Find all the zeros of the function. When there is ...
- pre cal - Given f(x)=x^4-7x^3+18x^2-22x+12 A: list all possible rational zeros B...
- pre cal - g(x) = x^2 - x -12 / x + 1 I know the division brings it to x -2 + -10...
- Algebra 2!!!! - Use the graph to shorten the list of possible rational zeros of...
- Pre-Calc - Find the zeros of the function algebraically. Show all work. f(x)=x^2...
- Pre-Calc - Find the zeros of the function algebraically. Show all work. f(x)=x^2...
- Math - I just wanted to double check that I am correct. 1.Find the zeros for the...
- Pre Calc - 7. The Sandusky Little League uses a baseball throwing machine to ...
- Math - f(x)=x64-4x^2+k. Find the values of k so thath the zeros of f satisfy the...
- Math - Find the Zeros of the following functions f(x) = x/3 +5 ^ That one is ...