Multiple choice

Which of the following equations has real and equal roots?

  1. 9x2 – 24x – 16 = 0

  2. 9x2 + 24x – 16 = 0

  3. 9x2 – 24x + 16 = 0

  4. 9x2 + 12x + 16 = 0
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

For real and equal roots, the discriminant D = b^2 - 4ac must be 0. For 9x^2 - 24x + 16 = 0, D = (-24)^2 - 4*9*16 = 576 - 576 = 0.

AI explanation

For a quadratic equation to have real and equal roots, its discriminant (b^2 - 4ac) must equal zero. For the equation 9x^2 - 24x + 16 = 0, the values are a = 9, b = -24 and c = 16. Calculating the discriminant gives (-24)^2 - 4(9)(16) = 576 - 576 = 0, proving the roots are real and equal.

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