Let's say this is our question:
Solve the equation x + 2 = 2x + 9
What we want is for x to be on its own, because then we can find out what x is.
First, we get rid of + 2. To do this, we subtract 2:
x + 2 - 2 = 2x + 9 - 2
(what we do to one side, we do to the other, so subract 2 from the other side as well)
Now, if we simplify, we get:
x = 2x + 7
Ok, x is on its own, but we still don't know what x is because of the 2x on the other side.
So, we subtract 2x from both sides:
x - 2x = 2x - 2x + 7
Simplifying, we get:
- x = 7
But now we have -x! So, we reverse the sign to get x. Remember, we do this on both sides!
x = - 7
So now we know! We can go back to our original equation and check if we're not sure:
- 7 + 2 = (2 x - 7) + 9
This comes to:
- 5 = - 14 + 9
Simplifying again:
- 5 = - 5
There! So now we know that we were right and x is - 7. To check your knowledge, take our quick quiz:
Comments