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#### karush

##### Well-known member

- Jan 31, 2012

- 2,723

(a) Show that $\overrightarrow{PQ}=\pmatrix{ 1\cr -2\cr 3\cr}$

$\overrightarrow{PQ}=\pmatrix{3\cr -3\cr 8\cr}-\pmatrix{2\cr -1\cr 5\cr}$

(b) The line $L_1$ may be represented by $r=\pmatrix{3\cr -3\cr 8\cr}+s\pmatrix{1\cr -2\cr 3\cr}$

i don't know this notation but it looks like $r=Q+\overrightarrow{PQ}$ so we are taking a point and adding a vector to it?

more ? to come on this...