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# Order of operations watch

1. When following the order of operations with for example:

3-cos^2(X)+6cos^2(X)=0

Why can we combine the cos^2(x) even though the 3-cos^2(x) should come first by the order of BIDMAS?
2. (Original post by JakeRStudent)
When following the order of operations with for example:

3-cos^2(X)+6cos^2(X)=0

Why can we combine the cos^2(x) even though the 3-cos^2(x) should come first by the order of BIDMAS?
Brackets,
Indices,
Division and Multiplication,

they are on the same level so doesn't matter which order you do them in
[3-cos^2(X)+6cos^2(X) = (3-cos^2(X)) +6cos^2(X) = 3+5cos^2(X)]
3. (Original post by Squirtle.U)
Brackets,
Indices,
Division and Multiplication,

they are on the same level so doesn't matter which order you do them in
[3-cos^2(X)+6cos^2(X) = (3-cos^2(X)) +6cos^2(X) = 3+5cos^2(X)]
Is the rule not if theyre on the same level you do them left to right?

For example 5-6+2 is not the same as 5-(6+2)?
4. (Original post by JakeRStudent)
Is the rule not if theyre on the same level you do them left to right?

For example 5-6+2 is not the same as 5-(6+2)?
No but remember 3 is a constant which has no affect on the cos^2(X)'s, another way to see this is in algebraic form..
Let Y=cos^2(X)
3-cos^2(X)+6cos^2(X)
Replacing the cos^2(X) with Y becomes
3-Y+6Y
This is a simple enough algebra
The result is
3+5Y
Now all you do is replace cos back in
Hence
3+5cos^2(X)
5. (Original post by JakeRStudent)
Is the rule not if theyre on the same level you do them left to right?

For example 5-6+2 is not the same as 5-(6+2)?
It is left to right if on the same level. However in your example you changed the sign of the "2" by putting it in brackets.
...
It may help to think of adding minus 6 instead subtracting 6
6. (Original post by JakeRStudent)
Is the rule not if theyre on the same level you do them left to right?

For example 5-6+2 is not the same as 5-(6+2)?
You have put the brackets in yourself there, they were not there to begin. For 5-6+2 we do 5-6=-1
so 5-6+2=-1+2=1.

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