Math Problem Statement

The function g is defined as g(x) = x^3 + (2 - a)x^2 - 2ax, where a is a constant. When the value of x is either 0, -2, or 8, the value of g(x) is 0. What is the value of a?

Solution

To determine the value of aa for which g(x)=0g(x) = 0 when x=0,2,x = 0, -2, and 88, we begin by evaluating g(x)g(x) at these points.

The function gg is given by: g(x)=x3+(2a)x22axg(x) = x^3 + (2 - a)x^2 - 2ax

First, evaluate g(x)g(x) at x=0x = 0: g(0)=03+(2a)022a0=0g(0) = 0^3 + (2 - a)0^2 - 2a \cdot 0 = 0

Since g(0)=0g(0) = 0, it does not provide any additional information about aa.

Next, evaluate g(x)g(x) at x=2x = -2: g(2)=(2)3+(2a)(2)22a(2)g(-2) = (-2)^3 + (2 - a)(-2)^2 - 2a(-2) g(2)=8+(2a)4+4ag(-2) = -8 + (2 - a)4 + 4a g(2)=8+84a+4ag(-2) = -8 + 8 - 4a + 4a g(2)=8+8=0g(-2) = -8 + 8 = 0

This simplifies to 0=00 = 0, giving no new information about aa.

Finally, evaluate g(x)g(x) at x=8x = 8: g(8)=83+(2a)822a8g(8) = 8^3 + (2 - a)8^2 - 2a \cdot 8 g(8)=512+(2a)6416ag(8) = 512 + (2 - a)64 - 16a g(8)=512+12864a16ag(8) = 512 + 128 - 64a - 16a g(8)=512+12880ag(8) = 512 + 128 - 80a g(8)=64080ag(8) = 640 - 80a

Since g(8)=0g(8) = 0: 64080a=0640 - 80a = 0 80a=64080a = 640 a=64080a = \frac{640}{80} a=8a = 8

Thus, the value of aa is 88.

Would you like more details or have any questions? Here are 5 questions you might ask next:

  1. How do you determine the roots of a polynomial equation?
  2. Can you explain how to factorize cubic polynomials?
  3. What are the properties of polynomial functions?
  4. How can the value of aa affect the shape of the graph of g(x)g(x)?
  5. What methods can be used to verify the roots of a polynomial equation?

Tip: Always check the given conditions in a problem to see if they provide independent equations, which can simplify solving for unknowns.

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Math Problem Analysis

Mathematical Concepts

Polynomial functions
Roots of polynomials

Formulas

Polynomial function g(x) = x^3 + (2 - a)x^2 - 2ax

Theorems

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Suitable Grade Level

Grades 10-12