Verified Solution Mathematics Quadratic Equations

The roots of the quadratic equation x² + ax + b = 0 are 1 and -2. Find the roots of the equation x² + (a+b)x + b = 0.

8 views 3 helpful Updated Jul 14, 2026
Solution ✔ Verified
  • A2, -1
  • B1, -2
  • C2, 1
  • D-2, -1
Explanation

For x² + ax + b = 0 with roots 1 and -2: Sum of roots = 1+(-2) = -1 = -a, so a = 1. Product of roots = 1*(-2) = -2 = b, so b = -2. The second equation is x² + (a+b)x + b = 0. Substitute a=1 and b=-2: x² + (1+(-2))x + (-2) = 0 => x² - x - 2 = 0. Factoring this equation, (x-2)(x+1) = 0. So, the roots are 2 and -1.

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