Math Problem Statement

If x = –4 and x = –3 are the roots of the equation ax2 + 7x + b = 0, find the value of a and b.

Solution

Given that x=4x = -4 and x=3x = -3 are the roots of the equation ax2+7x+b=0ax^2 + 7x + b = 0, we can use Vieta's formulas, which state that for a quadratic equation ax2+bx+c=0ax^2 + bx + c = 0 with roots r1r_1 and r2r_2:

  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 of the roots

For this equation, the sum of the roots is: 4+(3)=7-4 + (-3) = -7 Using Vieta's formula for the sum of the roots: 7a=7-\frac{7}{a} = -7 Solving for aa: a=1a = 1

Step 2: Product of the roots

The product of the roots is: 43=12-4 \cdot -3 = 12 Using Vieta's formula for the product of the roots: ba=12\frac{b}{a} = 12 Since a=1a = 1, we have: b=12b = 12

Conclusion

The values of aa and bb are: a=1andb=12a = 1 \quad \text{and} \quad b = 12

Would you like further details on the steps? Here are some related questions:

  1. How would the values of aa and bb change if the roots were different?
  2. What happens if aa is not equal to 1?
  3. How does Vieta's formula apply to equations of higher degrees?
  4. Can Vieta's formulas be used if the roots are complex numbers?
  5. What is the significance of the coefficient values in a quadratic equation?

Tip: Always verify your answers by plugging the roots back into the equation to check if it equals zero.

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Math Problem Analysis

Mathematical Concepts

Algebra
Quadratic Equations
Vieta's Formulas

Formulas

Sum of roots: r1 + r2 = -b/a
Product of roots: r1 * r2 = c/a

Theorems

Vieta's Formulas

Suitable Grade Level

Grades 9-10