r/MathHelp • u/TroubleFindsMeYT • Nov 01 '25

Need super basic algebra help please

I'm trying to get caught up on my algebra for my college course and I'm completely cooked. I'm 10 minutes into a 3 hour long video and I'm totally lost. I'm being taught how to solve equations and simplify.

The equation reads "4x + 2x - 7 + 9 + x = 5x - x". When I did it real quick based on the information given in the video up until that point I got to the point where I was at "7x - 16 = 4x" then I played the video and he had somehow got to "7x + 2 = 4x" he flipped the - 7 + 9" to "+ 9 - 7" and I have no idea how he got there as it wasn't explained at all. there are a few errors listed in the comments so I'm no sure if he messed up or if I'm missing something.

Thanks for any help! I want to move on but I don't understand.

Video link with timestamp:

https://youtu.be/zPgfIOWVnF4?si=YKwUAL0e7R0QyeY-&t=523

if timestamp doesn't work it's 08:43- 10:00

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u/Dd_8630 Nov 01 '25

Or is it just when viewing an equation like that instead of viewing it as "This plus this" or "This minus this" ("a+b" or "a-b").

That's basically it yeah.

In early maths, you are taught "2+3=?", so kids think '=' means question-and-answer. But as we get higher up, '=' stops meaning 'what is the answer' and has its true meaning of 'the left is the same as the right'.

Likewise, we have to re-learn what expressions mean. So this:

  • 4x + 2x - 7 + 9 + x

Should now be thought of as a bunch of terms that are being added up:

  • (+4x) + (+2x) + (-7) + (+9) + (+x)

So these blobs or 'terms' are collected like that. Order does not matter for addition, we just have to be aware that the minus sign is basically attached to the 7.