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To solve these simulataneous equations we need to use substitution:
If 2x + y = 13 then y = 13 - 2x
Therefore 3x - y = 12 can be rewritten as 3x - (13 - 2x) = 12
We can expand these brackets and solve for x:
3x - 13 + 2x = 12
-> 5x = 25
--> x = 5
Now we have the value of x, we can subsitute this into either of the initial equations to find the value of y:
2(5) + y = 13
--> 10 + y = 13
--> y = 3
3(5) - y = 12
--> 15 - y = 12
--> y = 3
You can then check your values are correct by subsituting them into either of the equations:
2(5) + (3) = 13
10 + 3 = 13 --> it works!see more
This is the lowest/simplest ratio of the molecule.
For example propene has the formula C3H6 - if we look a the subscript numbers (the ones down here!) we can see that smaller numbers are possible. It is important to know the relationship between these numbers. In this case you can write this simply as CnH2n. Therefore the empirical formula for propene is CH2.
Another example is propane which is C3H8. We can work out that the relationship is as follows: CnH2n+2 and therefore the empirical formula is CH4.see more
A scalar quantity has magnitude only - for example distance.
A vector has magnitude and direction - for example gravity (acceleration towards the centre of Earth).