Here's the question you clicked on:
burhan101
x intercept for this function
\[\huge y=x^3-9x^2+15x+4\]
this is unfactorable?
Any particular method they want you to use? Do they specify factoring?
No but isnt that the only way?
Graphing is the easiest.
Graph that bad boy. Look for where it crosses the x axis. Doneso.
no i have to use an algebraic method
because like say on an exam, i cant graph that
Possible rational roots are :
Okay then your best best is to use the rational root theorem to list possible rational roots. Then check each one to see if it is a valid root.
Use synthetic division to see if any of those are actual roots.
Mertsj is correct. The way he got those possible roots is: A: Make a list of factors for the last number (In this case, it's 4) B: Make a list of factors for the first coefficient (In this case, it's 1) Possible rational roots must be of the form \(\huge \frac{\text{things in the first list}}{\text{things in the second list}}\)
So the best approach would be to find where y changes sign. Then you would know there is a root between those two values and you could hone in on it by trial and error. Of if you know calculus, you could use the derivative. What class is this for?
they want you to bruteforce using newton's more than likely