SOLUTION: in my math class we are solving linear equations using the subtitution method there two problems i didnt get, this is one x-3y=0 3x+y=7 this is the set of numbers and we have

Algebra ->  Coordinate Systems and Linear Equations  -> Lessons -> SOLUTION: in my math class we are solving linear equations using the subtitution method there two problems i didnt get, this is one x-3y=0 3x+y=7 this is the set of numbers and we have      Log On


   

Question 179040This question is from textbook
: in my math class we are solving linear equations using the subtitution method
there two problems i didnt get, this is one
x-3y=0
3x+y=7
this is the set of numbers and we have to solve for the x and y values of the number equations
 This question is from textbook

Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!



Start with the given system of equations:

system%28x-3y=0%2C3x%2By=7%29



Now in order to solve this system by using substitution, we need to solve (or isolate) one variable. I'm going to solve for y.



So let's isolate y in the second equation

3x%2By=7 Start with the second equation


y=7-3x Subtract 3x from both sides


y=-3x%2B7 Rearrange the equation


---------------------

Since y=-3x%2B7, we can now replace each y in the second equation with -3x%2B7 to solve for x



x-3%2Ahighlight%28%28-3x%2B7%29%29=0 Plug in y=-3x%2B7 into the first equation. In other words, replace each y with -3x%2B7. Notice we've eliminated the y variables. So we now have a simple equation with one unknown.



x%2B%28-3%29%28-3%29x%2B%28-3%29%287%29=0 Distribute -3 to -3x%2B7


x%2B9x-21=0 Multiply


10x-21=0 Combine like terms on the left side


10x=0%2B21Add 21 to both sides


10x=21 Combine like terms on the right side


x=21%2F10 Divide both sides by 10 to isolate x




-----------------First Answer------------------------------


So the first part of our answer is: x=21%2F10


Since we know that x=21%2F10 we can plug it into the equation y=-3x%2B7 (remember we previously solved for y in the second equation).


y=-3x%2B7 Start with the equation where y was previously isolated.


y=-3%2821%2F10%29%2B7 Plug in x=21%2F10


y=-63%2F10%2B7 Multiply


y=7%2F10 Combine like terms (note: if you need help with fractions, check out this solver)



-----------------Second Answer------------------------------


So the second part of our answer is: y=7%2F10







-----------------Summary------------------------------

So our answers are:

x=21%2F10 and y=7%2F10

which form the point