CA Foundation · Quantitative Aptitude · Equations
If x + y + z = 6, x − y + z = 2 and 2x + y − z = 1, what is the value of x + 2y + 3z?
The value is 14. Adding and subtracting the first two equations gives x + z = 4 and y = 2. The third equation then gives x = 1 and z = 3. Therefore x + 2y + 3z = 1 + 4 + 9 = 14.
- A11
- B12
- C16
- D14Correct
Explanation
Adding the first two equations gives 2x + 2z = 8, so x + z = 4, and subtracting them gives y = 2. The third equation becomes 2x − z = −1. Adding x + z = 4 gives 3x = 3, so x = 1 and z = 3. Check in the second equation: 1 − 2 + 3 = 2. So x + 2y + 3z = 1 + 4 + 9 = 14.
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