MATRICES - TRANSFORMS
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For details see post on
26-Feb-2015 at 6:00 am.
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Linear algebra here. So I would like to understand this 1-1 and
onto of a matrix. Let's say we have a mapping of T: R3-->R2
where T(x1,x2,x3)=(x1+x3,x2-2*x3)<---R2 this not 1-1 since
DimNul(A)=1. Which makes the Ker(T)={1}. T is onto simply because
there is a solution. Or because rank(A)=2. (No zero rows) but if we
had a mapping o R3-->R3 then it won't be 1-1 nor onto, right?
Can a matrix be onto but not 1-1 and the other way around?
GIVING BELOW THE GENERAL TEST PROCEDURE FOR YOUR PROBLEM | |||||||
HOW TO CHECK A L.T.MATRIX FOR ONE TO ONE & ON TO | |||||||
T[U]=M*U=V | |||||||
T[X1,X2,X3]=M*[X1,X2,X3]=[X1+X3,X2-2X3]…SO WE GET | |||||||
M= | U= | ||||||
1 | 0 | 1 | * | X1 | = | X1+X3 | |
0 | 1 | -2 | X2 | X2-2X3 | |||
X3 | |||||||
ONE TO ONE …. | CHECK LINEAR INDEPENDENCE OF COLUMN VECTORS.. | ||||||
WE HAVE 3 COLUMN VECTORS IN R2 OF DIMENSION 2 | |||||||
SO THEY ARE LINEARLY DEPENDENT . | |||||||
SO THE TRANSFORM CAN NOT BE ONE TO ONE …. | |||||||
ON TO … | CHECK WHETHER THE COLUMN VECTORS SPAN THE RANGE SPACE | ||||||
NR3=R3+4R1 | |||||||
1 | 0 | 1 | |||||
0 | 1 | -2 | |||||
WE FIND THAT THERE ARE 2 L.I. CONUMNS . | |||||||
WE NEED 2 L.I. VECTORS IN R2 TO SPAN R2 . | |||||||
SO THEY CAN SPAN R2 | |||||||
SO THE TRANSFORM IS ON TO . |
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