Math Problem Statement

The polynomial of degree 4,
P ( x ) has a root of multiplicity 2 at
x

4 and roots of multiplicity 1 at
x

0 and
x

− 3 . The graph passes through the point
( − 1 , − 200 ) .

Find a formula for
P ( x ) .

P ( x )

Solution

The polynomial P(x)P(x) has the following characteristics:

  • A root of multiplicity 2 at x=4x = 4.
  • Roots of multiplicity 1 at x=0x = 0 and x=3x = -3.
  • It passes through the point (1,200)(-1, -200).

Step 1: Express P(x)P(x) in factored form

Given the information about the roots and their multiplicities, the polynomial can be written as: P(x)=a(x4)2(x)(x+3)P(x) = a(x - 4)^2(x)(x + 3) where aa is a constant to be determined.

Step 2: Use the point (1,200)(-1, -200)

We know that P(1)=200P(-1) = -200. Substitute x=1x = -1 into the polynomial to solve for aa:

P(1)=a(14)2(1)(1+3)=200P(-1) = a(-1 - 4)^2(-1)(-1 + 3) = -200

Simplifying the expression inside the parentheses: (14)=5,(1+3)=2(-1 - 4) = -5, \quad (-1 + 3) = 2 P(1)=a(5)2(1)(2)=200P(-1) = a(-5)^2(-1)(2) = -200

Now calculate the powers and products: P(1)=a(25)(1)(2)=200P(-1) = a(25)(-1)(2) = -200 P(1)=50a=200P(-1) = -50a = -200

Step 3: Solve for aa

a=20050=4a = \frac{-200}{-50} = 4

Step 4: Write the final formula

Now substitute a=4a = 4 back into the factored form of the polynomial:

P(x)=4(x4)2x(x+3)P(x) = 4(x - 4)^2 x (x + 3)

This is the formula for the polynomial P(x)P(x).

Would you like further details or have any questions?

Here are 5 related questions to explore:

  1. How do we know the degree of the polynomial based on the roots and their multiplicities?
  2. What does it mean for a root to have multiplicity 2 versus multiplicity 1?
  3. How can you find the constant aa if a point is not given?
  4. How do changes in the coefficient aa affect the graph of the polynomial?
  5. How would the polynomial change if another point on the graph was given instead of (1,200)(-1, -200)?

Tip: Always verify your solution by substituting points given in the problem into your equation.

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Math Problem Analysis

Mathematical Concepts

Polynomial Functions
Algebra
Roots of Polynomials

Formulas

Factored form of a polynomial: P(x) = a(x - r1)^m1(x - r2)^m2 ...
Finding a polynomial constant using a given point: P(x) = a(x - r1)^m1(x - r2)^m2 ...

Theorems

Fundamental Theorem of Algebra
Multiplicity of Roots

Suitable Grade Level

Grades 10-12