CA Foundation · Quantitative Aptitude · Equations
If one root of the equation x² − 7x + k = 0 is 3, what is the other root and the value of k?
The other root is 4 and k = 12. The sum of the roots equals 7, so the second root is 7 − 3 = 4, and k is the product of the roots, 3 × 4 = 12. Substituting x = 3 confirms the equation is satisfied.
- AOther root 4, k = 12Correct
- BOther root 4, k = 7
- COther root 10, k = 30
- DOther root 3, k = 9
Explanation
Sum of roots = 7, so the other root = 7 − 3 = 4. Product = k = 3 × 4 = 12. Check: 9 − 21 + 12 = 0. The option with k = 7 confuses k with the sum of roots.
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