Solve the sysyem by substitution.
4x-7y=15
x-3y=5
The answers are (2,-1)
Help?

Question

Solve the sysyem by substitution.  
4x-7y=15
x-3y=5
The answers are (2,-1)
Help?

ganeshie8 · Answer

from the second equation,

x-3y = 5
x = 5 + 3y

ganeshie8 · Answer

substitute this x value in first equation

ganeshie8 · Answer

4(5+3y) - 7y = 15

ganeshie8 · Answer

you can solve above for y ?

anonymous · Answer

I keep coming up with y=-1

ganeshie8 · Answer

thats the answer says also (: good work :)

anonymous · Answer

Oh...never mind.  That is the y

anonymous · Answer

And then sub the y and solve for x

ganeshie8 · Answer

yup soo many subs...  thats why its called subb method !!

anonymous · Answer

So my main problem is there is so many way to do this and sometimes the fractions get so ugly

anonymous · Answer

I would rather just use elimination...so much easier

ganeshie8 · Answer

yes i agree.... i prefer elimination most of the times... substitution i feel  long process lol

anonymous · Answer

Like taking 4x-7y=15
-7y=-4x+15
y=4/3x-15/7
And so on, and so on....
It just gets so jumbled

anonymous · Answer

Anyway...thank you very much!!

anonymous · Answer

I meant y=-4/7-15/7 :)

ganeshie8 · Answer

you took the deadly poison... 
substituting y=-1 in 2nd equation is somewhat simple :
x-3y=5

x-3(-1) = 5
x + 3 = 5
x = 2

;)