SOLUTION: Find all x- intercept: f(x)=24x^3-14x-20x Please show me step by step to get the answer. Thanks

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: Find all x- intercept: f(x)=24x^3-14x-20x Please show me step by step to get the answer. Thanks      Log On


   



Question 463988: Find all x- intercept:
f(x)=24x^3-14x-20x
Please show me step by step to get the answer. Thanks

Answer by lwsshak3(11628) About Me  (Show Source):
You can put this solution on YOUR website!
Find all x- intercept:
f(x)=24x^3-14x-20x
I will assume you meant 14x to be 14x^2 because equations are not usually written as given
...
f(x)=24x^3-14x^2-20x
set f(x)=0
24x^3-14x^2-20x=0
simplify by dividing by 2
12x^3-7x^2-10x=0
factor out x
x(12x^2-7x-10)=0
x=0
(12x^2-7x-10)=0
Use quadratic formula to solve (12x^2-7x-10)=0
..
x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
..
a=12, b=-7, c=-10
x=[-(-7)ħsqrt((-7)^2-4*12*(-10))]/2*12
x=[7ħsqrt(49+480)]/24
x=[7ħ23]/24
x=30/24=5/4
or
x=-16/24=-2/3
x-intercepts: (0,5/4,-2/3)