Multiple choice

A person is asked to choose a, b, c (distinct) from a set x = {1, 2, 3, 4, 5} to form quadratic equation of the form ax2 + bx + c =0, such that roots are real. How many equations can be formed?

  1. 14

  2. 12

  3. 18

  4. 16
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

For ax^2 + bx + c = 0 to have real roots, b^2 - 4ac must be nonnegative. Checking distinct choices from 1 through 5 gives 14 ordered triples satisfying this condition.

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