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Exercise 1195Linear algebra › Vector spaces and subspacesL1Added 3 Nov 2026

Image of a basis under a linear map

#basis#image#linear map

Statement

Let f:R2→R3f:\mathbb{R}^2\to\mathbb{R}^3 be the linear map defined by f(1,0)=(1,2,3)f(1,0)=(1,2,3) and f(0,1)=(0,1,1)f(0,1)=(0,1,1). Compute a basis and the dimension of Im⁡f\operatorname{Im} f.

Hint

The image of a basis spans the image. Then reduce to a basis.

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Solution

Generators. Im⁡f=span⁡((1,2,3),(0,1,1))\operatorname{Im} f=\operatorname{span}((1,2,3),(0,1,1)).

Independence. The two vectors are not proportional, so they are independent.

Conclusion. A basis of Im⁡f\operatorname{Im} f is ((1,2,3),(0,1,1))((1,2,3),(0,1,1)), and dim⁡Im⁡f=2\dim\operatorname{Im} f=2.

Remark. Im⁡f\operatorname{Im} f is a plane in R3\mathbb{R}^3.