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CHAPTER 3.4

In this chapter onstructirf^ and

Pupils should be able to:
• construct simple linear
Solving Equations
equations with integer
coefficients
• solve linear equations
where unknowns are on
We form equations and solve them in many situations. We can use equations
one side only
to calculate a phone bill, plan a fundraising event at school or to work out the
price at which I should sell my products to earn a profit if I open a shop.

When we give a value to an algebraic expression, we get an equation. Let us
learn how to formulate and solve equations.

3.4.1 Solving equations using trial

and error

We can use trial and error to determine the value of x that satisfies the
equation.

Example 1

Amazing O x + S = 7
Mathematician Solution
Substitute values for x into the equation such that the value on the LHS is
I The equal sign (=) was
equal to the value on the RHS.
invented nearly 500
years ago by the Welsh If X = 1, LHS = 1+5 = 6. LHS RHS, so x = 1 is not a solution of the
equation
mathematician Robert
Recorde. If X = 2, LHS = 2 + 5 = 7. LHS = RHS, so x = 2 is the solution of the
He invented it because he equation.
was tired of always having If X = 3, LHS = 3 + 5 = 8. LHS 9^ RHS, so x = 3 is not a solution of the
to write "is equal to" in
equation
his equations.
So, X = 2 satisfies the equation x + 5 = 7.
He chose the two lines
because "no two things
X * + 5 Is it equal to 7?
can be more equal".
1 1 +5 = 6 X
2 2 + 5 = 7 3
3 3 + 5 = 8 X

UNITS I Introduction to Algebra and Equations