In: Advanced Math
T/F
1) The function f(x) = x1 − x2 + ... + (−1)n+1xn is a linear function, where x = (x1,...,xn).
2) The function f(x1,x2,x3,x4) = (x2,x1,x4,x3) is linear.
3) For a given matrix A and vector b, equation Ax = b always has a solution if A is wide
1) If
and
and
is scalar, then

Therefore,
is linear (TRUE).
2) If
and
and
is scalar, then

Therefore,
is linear (TRUE).
3) Consider the wide matrix

and the vector

If
has a solution then we get

which means

But the first equation itself implies
, so that the system above can not have any solution. Thus,
the statement in question is FALSE.