SOLUTION: y=3x-5 y=-2x-15 how to use the substitution method on these equations.

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Question 1050023: y=3x-5 y=-2x-15
how to use the substitution method on these equations.
Found 3 solutions by josgarithmetic, advanced_Learner, ikleyn:
Answer by josgarithmetic(39625)   (Show Source): You can put this solution on YOUR website!
Substitute for y.

-steps not shown-

x=-2
Answer by advanced_Learner(501)   (Show Source): You can put this solution on YOUR website!
y=3x-5 y=-2x-15
how to use the substitution method on these equations.

Solved by pluggable solver: SOLVE linear system by SUBSTITUTION
Solve:
We'll use substitution. After moving -1*y to the right, we get:
, or . Substitute that
into another equation:
and simplify: So, we know that y=-11. Since , x=-2.

Answer: .
Answer by ikleyn(52852)   (Show Source): You can put this solution on YOUR website!
.
y=3x-5 y=-2x-15
how to use the substitution method on these equations.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 

You have two equations

y =  3x -  5,    (1)
y = -2x - 15.    (2)

You just have "y" expressed via "x" in the equation (1): y 3x-5.
Simply substitute it instead of "y" into the second equation. You will get

3x - 5 = -2x -15.   (3)

Now you have a single equation for one unknown "x" only.

Simplify and solve it.



I can express this procedure in other words.

Sinse the left sides of the equations (1) and (2) are identical, their right sides are equal:

3x - 5 = -2x -15.   (4)

You get the sane equation as (3).

Now simplify and solve it.


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