Slove y=-8 -2x-2y=14 by substitution

Question

Solve the system y=-8 -2x-2y=14 substitution 

Answer 1

y = -8

-2x - 2y = 14

As y is already isolated and given in the first equation, substitute its value in the second equation.

-2x - 2(-8) = 14

2x = 16 - 14

x = 2

x = 1

Answer: (1, -8)

Answer 2

Hi, Ace,

     Here is an example of my own:  Let y= -10   -3x-3y=39.   Where you see "y" in the second equation, you enter -10.

-3x-3(-10)=39       Simplify it.

 

-3x+30=39      Solve for "x," by subtracting 30 from both sides of the equal sign.

 

-3x + 30 -30= 39-30     Simplify it.

 

-3x= 9     Divide both sides of the equation by the number next to "x."

-3/-3 x= 9/-3

 

x=-3    Now your problem can be worked the same way.

 

y=-8    and -2x-2y=14             Substitute -8 for "y" in the second equation.

-2x-2(-8)=14                           Simplify it.

-2x+16=14                             Solve for x by subtracting 16 from both sides of equal sign.

-2x= 14-16

-2x= -2                          Divide both sides of the equation by -2, the number next to "x." 

 

I will let you finish this problem.

 

Also, don't forget to check your work by substituting your answers for "x" and "y" back into the original equation to see if it works.  Your left side of your equation should also equal to 14.  14=14   check

 

If I have helped you, please give me a thumbs up.

                                                    Susan C.

Answer 3

Please elaborate

If the question is

 

1st equation              y = -8 -2x

and 2nd equation       -2y = 14

 

?

If yes then from 1st equation we know that   

 

              y = -8 -2x

Into 2nd equation, Instead of writing "y", just write "-8-2x"

 

2nd equation::         -2 times (-8-2x) = 14

 

                                -2 times -8   -  2 times 2x  = 14

                                 +16 +4x = 14

                                       +4x = 14 -16

                                       +4x = -2

                                          x = -2 / 4

                                          x = -1/2

 

Put this value in 1st or 2nd equation to get "y"

 

             y = -8-2x

             y = -8 - 2 times (-1/2)

             y = -8 + 1

             y = -7

 

Do bother for more explanation!