QUESTION 4
The given system of linear equations are,

and

We put equation (1) into equation (2) to obtain,

We expand to get,

Group like terms to get,

Simplify to get,

Divide both sides by -13 to get,

Put the value of x into equation (1) to get,


The solution is

QUESTION 5
The given system of linear equations are

and

We make y the subject in equation (1) to get,

Put equation (3) into equation (2) to get,

We expand to get,

We group like terms to get,

This implies that,

We divide both sides by -9 to get,

Put the value of x in to equation 3 to get,


Therefore the solution is

QUESTION 6
The given equations are,

and

Make x the subject in equation (2) to get,

Put equation (3) into equation (1) to get,

We expand to get,

We group like terms to obtain,

.Simplify to get,

Divide through by -16 to get,

Put the value of y into equation (3) to get,


Therefore