Thread: Basic Factorising

Ok for some reason i can do the more complicated stuff but was never taught the simple stuff because our teacher assumed we would know.

Anyone show me how to factorise out x²+5x & 3x²-60x

Is it as simple as x(x+5) and 3x(x-60)?

And what if the numbers first e.g 100-x² would it just be the same thing as before just different order? (10-x)(10+x)

Yes, you're absolutely correct!

Just be careful though.

3x²-60x does not factorise to 3x(x-60)

3x²-60x factorised is 3x(x-20)

oh ok but can 3x²-60x also factorise to x(3x-60) or does the bigger number always have to start or something?

This method is termed 'Bringing out the Common factor', so yes 3x²-60x can be factorised to x(3x-60).

However, do you notice that another common factor exists in the brackets? It's 3. So for the expression to be fully factorised, we need to acknowledge both the common factors of x and 3 and bring them to the front of the brackets.

x(3x-60) = 3x(x-20)

Originally Posted by ZeroPunk

oh ok but can 3x²-60x also factorise to x(3x-60) or does the bigger number always have to start or something?

First of all, you should try and get the spelling correct. It would be known as "Factoring" or "Factor." Here is an example, "How do I factor the following problem..." or "Factoring seems difficult to me..." No sweat! I just wanted to let others understand you clearer.

What you want to do when your factoring is take the largest number that you can that will go into everything. So, in your case it was 3.

Problem Example:

6x² + 60x The largest number that can go into everything is 6 because 6 can go into 6 and 60. We also have an x for both terms. So 6x(x + 10) would be the answer.

Originally Posted by ElectroNerd

First of all, you should try and get the spelling correct. It would be known as "Factoring" or "Factor." Here is an example, "How do I factor the following problem..." or "Factoring seems difficult to me..." No sweat! I just wanted to let others understand you clearer.

What you want to do when your factoring is take the largest number that you can that will go into everything. So, in your case it was 3.

Problem Example:

6x² + 60x The largest number that can go into everything is 6 because 6 can go into 6 and 60. We also have an x for both terms. So 6x(x + 10) would be the answer.

There is nothing wrong with saying "Factorising" - in some countries (like Australia, where I am from), we consider "Factorising" to be the correct terminology instead of "Factoring".

Originally Posted by Prove It

There is nothing wrong with saying "Factorising" - in some countries (like Australia, where I am from), we consider "Factorising" to be the correct terminology instead of "Factoring".

Neat, I didn't realize that. Learn something new every day, eh?