Find \(k\) so that \(k(3,4)\) has \(y\)-component \(-12\), then give the vector.
Question 18
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A line uses direction vector \(\mathbf b=(2,-1,3)\). Give two non-zero scalar multiples for the same line direction, then explain which one reverses the parameter direction.
Question 19
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Solve \(3(2x,1-x)=(12,-3)\), then decide whether \((2x,1-x)\) points in the same direction as \((12,-3)\).
Question 20
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A vector \(\mathbf a=(2,-2,1)\) is multiplied successively by \(k\) and \(m\), giving \((-18,18,-9)\). Find \(km\), and describe the effect on direction and length.