Algebra 2

When you already have a number with x then it stays the same. When you're changing it different and adding new numbers then this is what you can get.
3t+ y=12 ty=t+4
3t stays the same and t by itself changes.

3t+4t=12 is incorrect. If you have the same letter (x,y,tz...etc) then the number before it changes. See here

4t+4=12 would be the answer. So therefore your answer would be :



3.) 4x+1=2

the answer would be x= .5 or 1/2 because in the equation
3x-y =2
y=x-1
the next step would be to substitute the y for x-1.
so it would be 3x - (x-1) = 2
then the distributive property.
3x-x +1 = 2
2x+1=2
-1 -1
2x=1
--------
2
x=.5 or 1/2

Serjio:

3x - y = 2
y = x - 1
When the expression x - 1 is substituted into the first equation for y, the resulting equation is

1.) 2x - 1 = 2

2.) 2x + 1 = 2

3.) 4x + 1 = 2

---------------------------------------------------------------------
Hi Serjio,
The professor has got jet lag and Bob was three-quarters right. Sorry guys. But I am very pleased that you both made an attempt.
When you substitute, this is what you get. It is VERY important that you remember to put the brackets in
3x - (x - 1) = 2
There is an invisable 1 between the - sign and the bracket.
3x -1(x-1) = 2
And a minus sign ALWAYS belongs to the number or letter that follows it.
So you have to simplify the bit that is in red.
3x -1*x -1*-1
-1*x = -x and -1*-1 = +1 so
3x -x +1 = 2
2x + 1 = 2
-----------------------------------------------------------------------------------------
Actually, I guess you could take a shortcut, When there is a minus sign outside a bracket you can change it to a plus if you change the sign of all the terms inside the bracket.
So -(x-1) becomes +(-x+1) = -x+1
----------------------------------------------------------------------------------------
Bob, there is only one answer for x and only one answer for y

Oh my ! I'm sorry, I knew I did something wrong but I was in a rush so I couldn't fix it. My apologies! Oh dear, I feel ridiculous now. A professor whom got an easy algebra questions wrong! Please forgive me and thank you Melody for correcting it. That would of been truly awful for hi,/her to have used any of our answers and to have gotten them wrong.