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Problem 7 - Entrance Test

If the distance from (4,k) to the line 3x - 4y + 5 = 0 is 3, then k equals

Correct: D

Distance formula: |3·4 - 4k + 5|/√(3²+4²) = |17-4k|/5 = 3. Thus 17-4k = ±15. Solving 17-4k=15 gives k=1/2 (rejected), 17-4k=-15 gives k=8. Closest integer pair 2 or 8.