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.