What are the roots of the polynomial x^2 + 2x - 8?

Practice Questions

Q1
What are the roots of the polynomial x^2 + 2x - 8?
  1. -4 and 2
  2. 4 and -2
  3. 2 and -4
  4. 0 and -8

Questions & Step-by-Step Solutions

What are the roots of the polynomial x^2 + 2x - 8?
  • Step 1: Start with the polynomial x^2 + 2x - 8.
  • Step 2: Look for two numbers that multiply to -8 (the last number) and add to 2 (the middle number).
  • Step 3: The two numbers that work are 4 and -2 because 4 * -2 = -8 and 4 + (-2) = 2.
  • Step 4: Rewrite the polynomial using these numbers: x^2 + 4x - 2x - 8.
  • Step 5: Group the terms: (x^2 + 4x) + (-2x - 8).
  • Step 6: Factor out the common terms: x(x + 4) - 2(x + 4).
  • Step 7: Now, factor out (x + 4): (x + 4)(x - 2).
  • Step 8: Set each factor to zero: x + 4 = 0 and x - 2 = 0.
  • Step 9: Solve for x: From x + 4 = 0, we get x = -4. From x - 2 = 0, we get x = 2.
  • Step 10: The roots of the polynomial are x = -4 and x = 2.
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