**3. Using the notation of Formula:**

Write down a general linear system of

a) two equations in two unknowns.

b) three equations in three unknowns.

c) two equations in four unknowns.

a) A general linear system of two equations in two unknowns can be written

as:

where x1 and x2 are the unknowns.

b) A general linear system of three equations in three unknowns can be written

as:

where x1, x2 and x3 are the unknowns.

c) A general linear system of two equations in four unknowns can be written as:

where x1, x2, x3 and x4 are the unknowns.