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) About Me  (Show Source):
You can put this solution on YOUR website!
Substitute for y.

-steps not shown-

x=-2

Answer by advanced_Learner(501) About Me  (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:
+system%28+%0D%0A++++3%5Cx+%2B+-1%5Cy+=+5%2C%0D%0A++++2%5Cx+%2B+1%5Cy+=+-15+%29%0D%0A++We'll use substitution. After moving -1*y to the right, we get:
3%2Ax+=+5+-+-1%2Ay, or x+=+5%2F3+-+-1%2Ay%2F3. Substitute that
into another equation:
2%2A%285%2F3+-+-1%2Ay%2F3%29+%2B+1%5Cy+=+-15 and simplify: So, we know that y=-11. Since x+=+5%2F3+-+-1%2Ay%2F3, x=-2.

Answer: system%28+x=-2%2C+y=-11+%29.

Answer by ikleyn(52852) About Me  (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.