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Question 557027: -7x+y=11
2x+4y=14
how do i solve this using substitution
Answer by Theo(13342)   (Show Source):
You can put this solution on YOUR website! your equations are:
-7x+y=11
2x+4y=14
use one of the equations to solve for one of the variables in terms of the other variable.
start with:
-7x + y = 11
add 7x to both sides of the equation to get:
y = 7x + 11
you have now solved for the variable of y in terms of x.
now substitute for y in the second equation of:
2x+4y=14 to get:
2x + 4*(7x + 11) = 14
simplify to get:
2x + 28x + 44 = 14
combine like terms to get:
30x + 44 = 14
subtract 44 from both sides of the equation to get:
30x = -30
divide both sides of the equation by 30 to get:
x = -30/30 which becomes:
x = -1
use that value of x in the first original equation to solve for y.
the first original equation is:
-7x+y=11
substitute -1 for x in that equation to get:
-7(-1) + y = 11
simplify to get:
7 + y = 11
subtract 7 from both sides of that equation to get:
y = 11 - 7 which becomes:
y = 4
your solution is:
x = -1
y = 4
substitute those values in the second original equation to confirm this answer is good.
the second original equation is:
2x+4y=14
substitute -1 for x and 4 for y to get:
2(-1) + 4(4) = 14
simplify to get:
-2 + 16 = 14
combine like terms to get:
14 = 14
this confirms the values for x and y are good because they provide solutions to both equations simultaneously,
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