Question

3x-4y and 7x-y=33 System of equations

Answer 1

Okay do :
 (1)3x-4y = 7
(2)7x - y = 33 -
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multiply one of the equations to get the y terms to be the same or the x terms to be the same . In this case it's easier to make the y terms the same . to do this you have to multiply the whole of 7x - y =33 by 4 .

This gives you :
3x -4y =7
28x -4y = 132 -  (when signs are the same you take away,when different you add)
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25x = 125 ( the -4y cancel out )
 divide both sides by 25 to give you the value of x

x= 5 .

Now substitute x=5 into either equation (1) or (2)
It should give you the same answer in both equations .

 (1)3x-4y = 7
so you should have :
 (3x5)-4y=7
15 -4y = 7
Take away 15 from both sides to get rid of the 15 .
-4y = (7-15)
-4y = -8
divide both sides by -4 to get the value of y .
y = 2 .

to check whether your values are correct substitute y = 2 and x=5 into equation (1) or (2) .

(2) 7x -y = 33
 (7x 5) -2
=35 -2 
=33 

(you can try both equations , it should work on both of the m)

I hope that was helpful :)