subtitution and Elimination #3b

Question

1)  y=-5x+2

     y=3x-14

 

2)  x+y=0

     5x+y=4

Answer 1

Andrea, 

 

 

    Jason's answers are good.  :)  

 

Randy B.

 

PS   If you will go to this website and work through the section on Systems of Equations, you will learn, understand, and soon be helping everybody in your class.  

 

https://www.khanacademy.org/math/algebra/systems-of-eq-and-ineq

Answer 2

1)

 

y = -5x + 2

y = 3x - 14

 

Set them both equal to each other since both are equal to y.

 

-5x + 2 = 3x - 14

+5x         +5x

 

2 = 8x -14

+14    +14

 

16 = 8x

 

x = 2  

 

y = 3(2)- 14 = -8

 

 

2)

x+y=0
5x+y=4

---------

Multiply the top by -1

 

-x - y = 0

5x + y = 4

 

Add the two equations.

 

5x-x = 4x, y - y = 0, 4 + 0 = 4 

4x = 4

x = 1

 

5(1) + y = 4

5 + y = 4

-5        -5

 

y = -1