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How does scalar multiplication affect the length of a vector precisely?

The length is multiplied by the absolute value of the scalar ∣c∣|c|. Specifically, 0<∣c∣<10 < |c| < 1 shortens the vector, ∣c∣>1|c| > 1 stretches it, and c=0c=0 yields the zero vector.

Conditions

  • Scalar multiplication operation
  • Considering magnitude/length changes

Reasoning, step by step

  1. Take the absolute value of the scalar multiplier.
  2. Multiply the original vector's norm by this value.
  3. Classify the result: shrinkage if factor < 1, expansion if factor > 1, nullification if factor = 0.

Example

Scaling a vector of length 5 by c=−0.5c=-0.5 results in a vector of length 5×∣−0.5∣=2.55 \times |-0.5| = 2.5 pointing in the opposite direction.

Common misconceptions

  • Using the signed scalar directly for length calculation (resulting in negative length).
  • Assuming direction affects the magnitude scaling factor.

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