Math Problem Statement

If 1/5 and -2 are respectively product and sum of the zeroes of a quadratic polynomial,find the polynomial

Solution

To find the quadratic polynomial given the product and sum of its zeroes, we can use Vieta's formulas.

Let the quadratic polynomial be of the form:

f(x)=ax2+bx+cf(x) = ax^2 + bx + c

For a quadratic equation, the relationships between the coefficients and the zeroes (roots) α\alpha and β\beta are given by:

  1. The sum of the zeroes α+β=ba\alpha + \beta = -\frac{b}{a}
  2. The product of the zeroes αβ=ca\alpha \beta = \frac{c}{a}

From the problem, we know:

  • The sum of the zeroes is 2-2, so: α+β=2\alpha + \beta = -2

  • The product of the zeroes is 15\frac{1}{5}, so: αβ=15\alpha \beta = \frac{1}{5}

Now, using these relationships, we can express the quadratic equation as:

f(x)=a(x2(α+β)x+αβ)f(x) = a(x^2 - (\alpha + \beta)x + \alpha \beta)

Substituting the given values:

f(x)=a(x2(2)x+15)f(x) = a(x^2 - (-2)x + \frac{1}{5})

Simplifying:

f(x)=a(x2+2x+15)f(x) = a(x^2 + 2x + \frac{1}{5})

To eliminate the fraction, multiply the entire equation by 5:

5f(x)=5a(x2+2x+15)=a(5x2+10x+1)5f(x) = 5a(x^2 + 2x + \frac{1}{5}) = a(5x^2 + 10x + 1)

Thus, the quadratic polynomial becomes:

f(x)=a(5x2+10x+1)f(x) = a(5x^2 + 10x + 1)

Since the leading coefficient aa is arbitrary, we can set a=1a = 1 for simplicity:

f(x)=5x2+10x+1f(x) = 5x^2 + 10x + 1

Thus, the quadratic polynomial is:

f(x)=5x2+10x+1f(x) = 5x^2 + 10x + 1


Would you like further details on any part of this process, or do you have any other questions?

Here are some related questions:

  1. How do you find the zeroes of a quadratic polynomial?
  2. What is the significance of the discriminant in determining the number of real roots of a quadratic equation?
  3. How can we modify the polynomial if the leading coefficient aa is different from 1?
  4. Can we derive the sum and product of the zeroes from a given quadratic equation?
  5. What would happen if the product of the zeroes was negative?

Tip: Always check the sign of the sum and product of zeroes to help determine the nature of the quadratic equation!

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Algebra
Quadratic Equations
Vieta's Formulas

Formulas

Sum of zeroes: α + β = -b/a
Product of zeroes: αβ = c/a
Quadratic equation form: f(x) = a(x^2 + bx + c)

Theorems

Vieta's Formulas

Suitable Grade Level

Grades 9-11