Math Problem Statement

Let f(x) be a fourth degree polynomial with co-coefficient of x power 4 is 1 such that f(-1) = -1, f(2) = -4, f(-3) = -9, and f(4) = -16. Then find the value of f(1).

Solution

We are given that f(x)f(x) is a fourth-degree polynomial of the form:

f(x)=x4+ax3+bx2+cx+df(x) = x^4 + ax^3 + bx^2 + cx + d where the leading coefficient of x4x^4 is 1. We are also provided with the following conditions:

f(1)=1,f(2)=4,f(3)=9,f(4)=16f(-1) = -1, \quad f(2) = -4, \quad f(-3) = -9, \quad f(4) = -16

Our goal is to find the value of f(1)f(1).

Step 1: Set up the equations

Using the conditions f(1)=1f(-1) = -1, f(2)=4f(2) = -4, f(3)=9f(-3) = -9, and f(4)=16f(4) = -16, we can substitute these values into the polynomial to create a system of equations.

1. For f(1)=1f(-1) = -1:

(1)4+a(1)3+b(1)2+c(1)+d=1(-1)^4 + a(-1)^3 + b(-1)^2 + c(-1) + d = -1 1a+bc+d=1a+bc+d=2(Equation 1)1 - a + b - c + d = -1 \quad \Rightarrow \quad -a + b - c + d = -2 \quad \text{(Equation 1)}

2. For f(2)=4f(2) = -4:

(2)4+a(2)3+b(2)2+c(2)+d=4(2)^4 + a(2)^3 + b(2)^2 + c(2) + d = -4 16+8a+4b+2c+d=48a+4b+2c+d=20(Equation 2)16 + 8a + 4b + 2c + d = -4 \quad \Rightarrow \quad 8a + 4b + 2c + d = -20 \quad \text{(Equation 2)}

3. For f(3)=9f(-3) = -9:

(3)4+a(3)3+b(3)2+c(3)+d=9(-3)^4 + a(-3)^3 + b(-3)^2 + c(-3) + d = -9 8127a+9b3c+d=927a+9b3c+d=90(Equation 3)81 - 27a + 9b - 3c + d = -9 \quad \Rightarrow \quad -27a + 9b - 3c + d = -90 \quad \text{(Equation 3)}

4. For f(4)=16f(4) = -16:

(4)4+a(4)3+b(4)2+c(4)+d=16(4)^4 + a(4)^3 + b(4)^2 + c(4) + d = -16 256+64a+16b+4c+d=1664a+16b+4c+d=272(Equation 4)256 + 64a + 16b + 4c + d = -16 \quad \Rightarrow \quad 64a + 16b + 4c + d = -272 \quad \text{(Equation 4)}

Step 2: Solve the system of equations

We now solve the system of four equations:

  1. a+bc+d=2-a + b - c + d = -2
  2. 8a+4b+2c+d=208a + 4b + 2c + d = -20
  3. 27a+9b3c+d=90-27a + 9b - 3c + d = -90
  4. 64a+16b+4c+d=27264a + 16b + 4c + d = -272

Let me solve this system.The solution to the system of equations is:

a=2,b=14,c=14,d=24a = -2, \quad b = -14, \quad c = 14, \quad d = 24

Thus, the polynomial f(x)f(x) is:

f(x)=x42x314x2+14x+24f(x) = x^4 - 2x^3 - 14x^2 + 14x + 24

Step 3: Find f(1)f(1)

Now, we substitute x=1x = 1 into the polynomial:

f(1)=(1)42(1)314(1)2+14(1)+24f(1) = (1)^4 - 2(1)^3 - 14(1)^2 + 14(1) + 24 f(1)=1214+14+24=23f(1) = 1 - 2 - 14 + 14 + 24 = 23

Thus, the value of f(1)f(1) is:

f(1)=23f(1) = 23

Let me know if you would like further details on the process.

Here are 5 related questions to expand your understanding:

  1. How do you find the roots of a polynomial equation?
  2. Can you explain the process of solving a system of nonlinear equations?
  3. How do the degrees of polynomials affect their graph shapes?
  4. What are the methods to factor a fourth-degree polynomial?
  5. How can you determine if a polynomial has any symmetry properties?

Tip: Always check for special cases like symmetry or known root values when solving polynomial problems. It may simplify the process.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Polynomials
System of Equations
Algebra

Formulas

General form of a fourth-degree polynomial: f(x) = x^4 + ax^3 + bx^2 + cx + d
Substituting known points to form a system of linear equations

Theorems

Solving a system of linear equations
Polynomial evaluation

Suitable Grade Level

Grades 10-12