Hi! When i did math back in the day i did not fully understand WHY math did what it did. I just learned the rules and saw them just as that, as rules, rather than something logic that i could understand. So im relearning and i need your help. I'm currently on algebra and have this equation:
x + 2y = 5
2x - y = 0
So the first thing i do is to subtract 2y on both sides: x = 5 -2y
I understand that since this is an equation, you can add and subtract if you do it on both sides. Since equation means that the both sides are the same.
Then i add it into the second equation: 2(5 -2y) - y = 0
Now, i do not understand WHY i put them in parentheses and not just into the equation like ths: 2 * 5 -2y - y = 0
Is it because i need to multiply it with both? If X where a single digit, could i just insert it without the parentheses?
My last question is, if i keep going with the equation i get this: 10 - 5y = 0
So my question is, can i just add the two Y:s together like that and can you always do it?
Here is how i did it for clarification.
2(5 -2y) - y
10 - 5y
x + 2y = 5
2x - y = 0
So the first thing i do is to subtract 2y on both sides: x = 5 -2y
I understand that since this is an equation, you can add and subtract if you do it on both sides. Since equation means that the both sides are the same.
Then i add it into the second equation: 2(5 -2y) - y = 0
Now, i do not understand WHY i put them in parentheses and not just into the equation like ths: 2 * 5 -2y - y = 0
Is it because i need to multiply it with both? If X where a single digit, could i just insert it without the parentheses?
My last question is, if i keep going with the equation i get this: 10 - 5y = 0
So my question is, can i just add the two Y:s together like that and can you always do it?
Here is how i did it for clarification.
2(5 -2y) - y
10 - 5y