Exercise · ZW-LINEAR-TRANSFORMATION-002 · ★☆☆ Basic
Which of these functions from \(\mathbb{R}^2\) to \(\mathbb{R}^2\) is linear?
Choose one option.
A \(T(x,y)=(x+1,\,y)\) B \(T(x,y)=(x^2,\,y)\) C \(T(x,y)=(xy,\,y)\) D \(T(x,y)=(x+y,\,x-y)\)
Show answer D. \(T(x,y)=(x+y,\,x-y)\)
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Explanation Only \((x+y,x-y)\) is a sum of multiples of \(x\) and \(y\), with no constants or powers. The others fail: \(x+1\) moves the origin, and \(x^2\) and \(xy\) are not additive.
A linear transformation \(T\) is a function between vector spaces that preserves addition and scalar multiplication.
\[T(u+v)=T(u)+T(v),\quad T(cu)=cT(u)\]
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