Linear equations & inequalities

Just substitute (x-8) for y in the second equation and solve for x. Watch the signs, that's why I'm suggesting the use of parenthesis.

Could you go step by step because I have very little algebra back ground.

2x - x-8 = 4
x - 8 = 4
x -8 + 8 = 4+8
x = 12

This is not one of the answers that is given to choose from.

I need step by step to solve this because I barely understand some of the algebra concepts.

I said to use parenthesis:

2x -(x-8) = 4

Try that?

Thank you for your help that is just what I needed to get started with the problem. The answer came out to the answer it was supposed too. I get the answer as x = -4.

Nice! but you didn't follow the initial directions or didn't understand them: Just substitute (x-8) for y in the second equation and solve for x. Watch the signs, that's why I'm suggesting the use of parenthesis.

Your work was excellent. It allowed the mistake to be readily apparent. Good work!

Another way:

If you had taken: 2x-y=4 and multiplied it by -1 you would get -2x+y=-4 which is equlivelent to y-2x=-4; Now Y is easier to substitute.


In fact I would not have even done the multiply by -1

Watch this method.

Just take 2x-(x-8) =4

make it equal to zero (subtract 4 from both sides)

2x-(x-8)-4 =0

Collect the x's: x's: 2 and -1 = 1x
Collect the numbers: 8 and -4 = 4

x+4 = 0 or x= -4

You can now do the problems much faster, but teach may not like you. Later on, you will learn to collect terms. Later on signs will make or break the problem. This method is much easier.

It basically says move everything to one side e.g =0
and collect terms, doing the sign changes etc in your head.

(x-4) (2x-5) =0
quadratic equations

Take X times 2X and X times -5 or X(2X - 5), which will become 2Xsquared -5X.

Now take -4 times 2X and -4 times -5 or -4(2X - 5), which will becomes -8X + 20.

So you have 2Xsquared - 5X - 8X + 20. Which now becomes 2Xsquared -13X + 20 = 0