One root of the quadratic equation x2 - 12x + a = 0, is thrice the other. Find the value of a?
Correct answer: B. 27
- A. 29
- B. 27
- C. 28
- D. 7
Explanation
Let the two roots be t and 3t. Their sum is t + 3t = 12, so 4t = 12 and t = 3; the roots are therefore 3 and 9, whose product is a = 3 x 9 = 27. The likely mistake is choosing a, which may come from treating the roots as 12 and 3 instead of using the given ratio.
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