When using substitution to solve the system below,which expression can be substituted into the second equation?

x + y =

x + y =

. Convert x + y = into slope intercept form [Y = MX + B]
Subtract x from both sides to get Y = -x +

. Substitute -x + for y in your second equation: x + (-x + ) = : Solve for X
Distribute: x -x + = Combine like terms: -x + = Subtract from both sides to get:
-x = –

Divide both sides of the equation by the coefficient of x (-) to get: x = /
Reduce / to get x = /

. Substitute your new value for X into the first equation: (/) + y =
multiply and / which is equal to dividing by two to get: + y =
Subtract from both sides to get: Y =

You now know that x = / and Y =

Check your work by substituting both values into either of your given equations:

(/) + =

+ =

=

Check.

Does this make sense?

HIH

Source(s):
Math Teacher

-Then BOTH the first and third can be substituted in.
You would have to get x by itself, making the expressions look like:
x=
THEN, you would substitute the x you solved for into the second one.
But like I said, to do substitution on equations, they have to be complete,
having the equals sign for you to be able to get x by itself.

-BOTH can be. Solve for x.
so it’d be x=(-y)/ and x=(-y)/.
Then choose one and plug the x into the second equation.
(:

Source(s):
maths knowledge