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JP16
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Homework Statement
The question states: "find all scalars c, if any exist such that given statement is true."
It also suggests trying to do without pencil and paper.
a) vector [c2, c3, c4] is parallel to [1,-2,4] with same direction.
b) vector [13, -15] is a linear combination of vectors [1,5] and [3,c]
c) vector [-1,c] is a linear combination of vectors [-3,5] and [6,-11]
The Attempt at a Solution
a) for it to be parallel, it has to be a scalar multiple of [1,-2,4] = x. and [c2, c3, c4] = y. then you can say ax = y. but wouldn't that give different values for all 3 c's? Let's say for example a=2. then 2x = y. then it would be:
i) c2 = 2*1
ii) c3 = 2*-2
iii) c4 = 2*4
which results in a different value of c in each. can i conclude that there DNE a such c?
b) the scalar multiple could be any real number for both vectors so c could be any real number?
c) 1[-3,5] + 1/3[6,-11] = [-1,4/3] so c = 4/3. this was achieved by trial and error. firstly is this even right? second, if its right, is there a algebraic way of doing it. it would have 3 unknowns and 2 equations.
at a glance seems pretty simple, or i just forgot some of the things i learned last year. any guidance would be appreciated.