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If the line \(\frac{x + 1}{4} = \frac{y + 2}{-3} = \frac{z - \alpha}{-2}\) passes through the point (-1,-2,-3) then the value of \(\alpha\) is

  • A.4
  • B.-4
  • C.3
  • D.-3
  • E.-2

Answer: D

\(\alpha =\) \(-3\).

For \((-1, -2, -3)\) the first two ratios are \(\frac{0}{4} = 0\) and \(\frac{0}{-3} = 0\), so the third must also be zero:

\[ \frac{-3 - \alpha}{-2} = 0 \;\Rightarrow\; \alpha = -3 \]

In fact the point is the line's own base point \((-1, -2, \alpha)\). \(\alpha = 3\) changes the sign, and the other values leave the third ratio non-zero.

A useful habit: when a point's first coordinates already match the line's base point, the parameter is 0, and every remaining coordinate must match too.

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