- #1
Fractal20
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- 1
Homework Statement
So the actual problem "Find the value of a for which the following system of linear equations has a solution"
2x + 4y + z = a
-4x -7y + 0 = 1
0 -1y -2z = 1
Homework Equations
The Attempt at a Solution
I thought one approach was to find a basis for the corresponding matrix and see what value of a would make that vector in the space formed by the basis. That is, see what value of a would make (a, 1, 1) in the range of the matrix.
But when I row reduce I get
2 4 1
0 1 2
0 0 0
So I want to say the 1st and 2cnd columns form a basis -> (2, -4, 0) and (4, -7, -1). But then some linear combination of these should equal (1, 0, -2). However, the first components of the basis appear to never be able to combine linearly to 1. That is there are no integers x,y such that 2x + 4y = 1 since -> x + 2y = 1/2...? I feel like I must be making a really trivial mistake??