+0  
 
0
2617
2
avatar

what is 4x + 8y = 20

-4x + 2y = -30

 Oct 14, 2015

Best Answer 

 #1
avatar
+10
  1. 4x+8y=20
  2. -4x+2y=-30

 

  1. 4x+8y= 20
  2. 4x-2y=30

 

(4x+8y)-(4x-2y)=20-30

10y=-10

y=-1

4x-8=20

x=7

 Oct 14, 2015
 #1
avatar
+10
Best Answer
  1. 4x+8y=20
  2. -4x+2y=-30

 

  1. 4x+8y= 20
  2. 4x-2y=30

 

(4x+8y)-(4x-2y)=20-30

10y=-10

y=-1

4x-8=20

x=7

Guest Oct 14, 2015
 #2
avatar+130540 
+6

4x + 8y = 20

-4x + 2y = -30

 

Adding the two equations, we get

 

10y  = -10       which implies that y = -1

 

Subbing this into the first equation, we have

 

4x + 8(-1)  = 20

 

4x - 8 = 20   add 8 to both sides

 

4x = 28     divide both sides by 4

 

x = 7

 

So...(x, y)   =  (7, -1)

 

 

cool cool cool

 Oct 14, 2015

3 Online Users

avatar
avatar