LESSON 9:Simultaneous Equations
Contents
Simultaneous linear equations
Introduction
In your previous unit you dealt with linear equations.You will also recall that these equations are of the first degree and their graphs are straight lines.We are moving further to simultaneous linear equations.These types of equations are like linear ones of the first degree but with two or more unknowns.
By the end of this unit you should be able to

Lesson content
Now consider the following equations;
 2f+1=23
 4(a3)=16
2xy=6 
x+y=5 
5x+2y=3 
2x+3y =1 
Do you notice any similarities and differences among the equations?You will see that the first two have just one unknown and the last two are in pairs having two unknowns.The first two are linear equations and the paired ones are called simultaneous linear equations. How do solve these equations? you can solve them the methods of either substitution,elimination or graphically. Let us examine the substitution method.There are three points to note
 make one of the unknowns or variables the subject of the other in one of the equations.
 substitute the expression into the other equation to find the unknown.
 Find the other unknown by substituting the value got in point 2 into the original equation.
Example
2xy=7 
x+y=2 
make x the subject
2xy=7 
x+y=2 
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