Expert: Paul Klarreich - 3/1/2009

Question
how do you find the x-intercept of the following examples:
y=2x^3-7x^2-3x+1
y=2x^2-10x-2
y=-2abs(x-5)=9

Answer
Questioner:   Sasha
Category:  Advanced Math
Private:  Yes
 
Subject:  x-intercept
Question:  how do you find the x-intercept of the following examples:
y=2x^3-7x^2-3x+1
y=2x^2-10x-2
y=-2abs(x-5)=9
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In all of them, you set the right side = 0 and solve the equation.

 
y = 2x^3 - 7x^2 - 3x + 1

Set  2x^3 - 7x^2 - 3x + 1 = 0 and solve, using what you learned in elementary school about solving polynomials (fourth grade, I think).

In this case, you will probably have to approximate the solutions.

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y = 2x^2 - 10x - 2

Set 2x^2 - 10x - 2 = 0, a quadratic.  You know what to do.
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y = - 2abs(x-5)-9     [is this what you meant?]

Set  - 2abs(x - 5) - 9  

Since abs(anything) is positive, -2 abs(..) is negative and so will be this function.

So what do you think about intercepts?


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