Math Problem Statement

If ax2+bx+c=0ax^2+bx+c=0A quadratic equation that has the two roots (5, -1) find a,ba,b

Solution

Given that ax2+bx+c=0ax^2 + bx + c = 0 is a quadratic equation with roots 55 and 1-1, we can apply Vieta's formulas, which state:

  1. The sum of the roots r1+r2=bar_1 + r_2 = -\frac{b}{a}
  2. The product of the roots r1r2=car_1 \cdot r_2 = \frac{c}{a}

Step 1: Sum and Product of Roots

For the roots r1=5r_1 = 5 and r2=1r_2 = -1:

  • The sum of the roots is 5+(1)=45 + (-1) = 4
  • The product of the roots is 5×(1)=55 \times (-1) = -5

Step 2: Substitute into Standard Form

The general form of a quadratic equation is: a(xr1)(xr2)=0a(x - r_1)(x - r_2) = 0

Substitute the roots 55 and 1-1 into the factored form: a(x5)(x+1)=0a(x - 5)(x + 1) = 0

Step 3: Expand the Expression

Now, expand the factored form: a(x5)(x+1)=a(x2+x5x5)=a(x24x5)a(x - 5)(x + 1) = a(x^2 + x - 5x - 5) = a(x^2 - 4x - 5)

Thus, the quadratic equation becomes: a(x24x5)=0a(x^2 - 4x - 5) = 0

Step 4: Compare with Standard Form

By comparing the equation a(x24x5)=0a(x^2 - 4x - 5) = 0 with the general form ax2+bx+c=0ax^2 + bx + c = 0, we can see:

  • b=4ab = -4a
  • c=5ac = -5a

Since cc is not given, aa can be any constant value. For simplicity, if we assume a=1a = 1, then:

  • b=4b = -4
  • c=5c = -5

Thus, the values of aa and bb are: a=1,b=4a = 1, \quad b = -4

Would you like more details or have any questions?


Here are 5 related questions to deepen your understanding:

  1. What happens if we change the sign of both roots?
  2. How would the equation change if a1a \neq 1?
  3. Can you derive the quadratic formula from Vieta’s formulas?
  4. How would you solve this equation using the quadratic formula?
  5. What are Vieta’s formulas used for in more advanced algebra?

Tip: Always check if factoring is the quickest method for solving quadratics before using the quadratic formula!

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Math Problem Analysis

Mathematical Concepts

Algebra
Quadratic Equations
Factoring
Vieta's Formulas

Formulas

ax^2 + bx + c = 0 (quadratic equation standard form)
r1 + r2 = -b/a (sum of roots)
r1 * r2 = c/a (product of roots)

Theorems

Vieta's Formulas

Suitable Grade Level

Grades 9-11