Solve y – 3x = 5 by the substitution method.
y + x = 3

Question

Solve y – 3x = 5 by the substitution method.
y + x = 3

anonymous · Answer

@ParthKohli , by substitution not elimination

parthkohli · Answer

My mistake. 

Subtracting $x$ from the second equation fetches ya
$ \color{Black}{\Rightarrow y  = 3  - x}$

Now substitute that back into the first equation:
$ \color{Black}{\Rightarrow (3 - x) - 3x = 5}$

anonymous · Answer

@ParthKohli now you got it

parthkohli · Answer

Yes. I sometimes fail absent-mindedly.

anonymous · Answer

ok..?

anonymous · Answer

@coolaidd you got it?

parthkohli · Answer

$ \color{Black}{\Rightarrow 3 - x - 3x = 5 }$

$ \color{Black}{\Rightarrow 3 - 4x = 5}$

I'd like coolaid to do the rest.

parthkohli · Answer

My weakness is that I am a lazy person, so I am not going to do everything else.

hero · Answer

I personally think @coolaidd should be trying some of these on her own.

anonymous · Answer

y-3x=5

y+x = 3


We have to put y= ..... or x = ..... on one side of both equations, hence
the easiest way is to put y on side since the first equation you can cancel the x on the left and add it on the right.

Here is our two new equations

y=3x+5 
y= 3-x

Since both equations are equivalent to y, we can make the equivalent for the same equation. (Basically we turn both into one single equation..)

   3x+5= 3-x
=> 3x+x = 3-5
=> 4x = -2
=> x = -1.5

Now subsitute -1.5 in the second original equation (since its the easiest) and now y=4.5
That's how you do it!

anonymous · Answer

sorry x = -0.5 and y = 3.5, sorry my mistake! that's the answer

anonymous · Answer

You can also do @ParthKohli did, but it doesn't really matter.

anonymous · Answer

@vmathhelp  but its good to follow the questions instructions