# could you show me an example of aljebra

Forums Junior Cert Maths could you show me an example of aljebra

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• #14440

could you show me an example of aljebra

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:could you show me an example of aljebra

• #14441 Anonymous

Algebra you mean…?

algebra is a way of representing a mathemathical equation with letters instead of numbers.

if mary is twice as old as john. In two years time john will be the same age mary is now. What age are both john and mary now?

to write this situation algebrically the age of the two people would be as follows

john's age =x (x is used here to represent the age john is in years ie x represents the unknown number)

mary's age =2x (x is used here to represent the age mary is in years ie 2x is x multiplied by 2 or twice x)

x+2=2x represents the statement In two years time john will be the same age mary is now.

to solve this equation and figure out what john and mary's ages

x-2x+2=0 (bringing 2x across the equals sign you change a plus to a minus)

x-2x=-2(again bringing 2 across the equals sign you change a plus to a minus)

-x=-2 (In algebra you add similar terms ie terms containing an x can be added together and numbers on there own can be added together.

<b><i>Note: you never add terms that are disimilar to each other ie numbers on there own with numbers containing x terms as this is equivilent to adding apples and oranges if you had a lunchbox full of 3 oranges and 2 apples I bet you wouldn't tell me that you had 5 oranges as you can obviously see the difference between an apple and an orange</i></b>

multiply across by -1 on both sides of the equation

x=2 (minus multipled by a minus is a plus)

also age is never negative you simply can't be -2 years of age

Therefore john is 2 years old and mary is 4 years old.

this is just one application of algebra but I hope it illustrats the basic concept ie that algebra is just a way of representing a number with a letter but algebraic equations can be worked out same way as normal equations with numbers however a new set of methods (set of rules) to solving these

equations must be applied

Hope this clarifies things a bit

If you have any specific questions relating to this area of maths please dont hesitate to post the problem on this forum and we'll see what we can do

Godel