SOLUTION: Solve system by substitution x-2y=-7 8x-2y=0

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Question 1064593: Solve system by substitution
x-2y=-7
8x-2y=0
Found 2 solutions by ikleyn, MathTherapy:
Answer by ikleyn(52800)   (Show Source):
You can put this solution on YOUR website!
.
Solve system by substitution
x-2y=-7
8x-2y=0
~~~~~~~~~~~~

x - 2y = -7, (1) 8x - 2y = 0. (2) From (1), express x = -7 + 2y and then substitute it into (2) replacing "x". You will get 8*(-7+2y) - 2y = 0, -56 + 16y - 2y = 0, 14y = 56 ----> y = {{56/14}}} = 4. Can you complete the solution from this point ?

On the Substitution method, Elimination method, Determinants' method for solving the systems of two linear equations
in two unknowns see the lessons
    - Solution of the linear system of two equations in two unknowns using determinant
    - Solution of the linear system of two equations in two unknowns by the Substitution method
    - Solution of the linear system of two equations in two unknowns by the Elimination method
    - Geometric interpretation of the linear system of two equations in two unknowns
in this site.

Also, you have this free of charge online textbook in ALGEBRA-I in this site
    - ALGEBRA-I - YOUR ONLINE TEXTBOOK.

The referred lessons are the part of this online textbook under the topic "Systems of two linear equations in two unknowns".

Answer by MathTherapy(10552)   (Show Source):
You can put this solution on YOUR website!

Solve system by substitution
x-2y=-7
8x-2y=0

x - 2y = - 7_____x = 2y - 7 ----- eq (i)
8x - 2y = 0 ------- eq (ii)
Note also that eq (ii) can remain as is, or it can be REDUCED by dividing it by its GCF, 2
8(2y - 7) - 2y = 0 -------- Substituting 2y - 7 for x in eq (ii) ------ eq (ii)
16y - 56 - 2y = 0
16y - 2y = 56
14y = 56

x = 2(4) - 7 ------ Substituting 4 for y in eq (i)