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Scalar multiplication and linear combinations

Mathematics — first biennium · Lesson

Biennium · Scientific profile

Scalar multiplication and linear combinations

Multiplying a vector by a scalar means multiplying both components. A linear combination such as 2u−v is built component by component using the same coefficients.

Key idea
Formula matematica
Similar example
Formula matematica

Prerequisites: Vectors in the plane

Goal: Multiply vectors by scalars and build linear combinations component by component.

What you need to know before the exercises

In this lesson: Multiply vectors by scalars and build linear combinations component by component.

New concept: Multiplying a vector by a scalar λ means multiplying both components by λ. A linear combination αu+βv is therefore built by scaling the vectors and adding corresponding components.

How to proceed: Write 2u first, then subtract v coordinate by coordinate. The minus sign in front of v changes both of its components.

You can already assume: Vectors in the plane.

Geometry view

Read the diagram

SVG
Geometry diagram for the exercise The three arrows show u, v and the combination w=2u−v in the same Cartesian plane. O u v w xyu=(2,-3)v=(-1,-4)w=(5,-2)

The three arrows show u, v and the combination w=2u−v in the same Cartesian plane.

Try it now

Calculate the combination without mixing x- and y-components.

Guided

Completed exercises: 0/5 · Correct on first attempt: 0

How to reason

Write 2u first, then subtract v coordinate by coordinate. The minus sign in front of v changes both of its components.

Data / situation: u=(2,-3), v=(-1,-4). Calculate w=2u-v.

Formula matematica
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What you need to know for Scalar multiplication and linear combinations

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