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Question 1064621: I'm having trouble on understanding how to solve a equasion. One example is 5x+3y=12. I don't know the steps to finding y.
Found 2 solutions by Fombitz, Theo:
Answer by Fombitz(32388)   (Show Source):
You can put this solution on YOUR website! You choose an x, solve for y.
This is the equation of a straight line so you only need two points to graph it.
So when  ,
So ( , ) is a point on the line.
When  ,
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Plot those two points and draw the straight line.
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You could also use the x and y intercepts.
When ,
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Either way you get the same line,
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Answer by Theo(13342)  (Show Source):
You can put this solution on YOUR website!
the key to solving equations is to move the variables and constants around until the variable that you want to solve for is on one side of the equation and the rest of the variables and constants are on the other side of the equation.
in this example:
start with 5x + 3y = 12
subtract 5x from both sides of the equation to get:
5x + 3y - 5x = 12 - 5x
combine like terms to get:
3y = 12 - 5x
divide both sides of the equation by 3 to get:
3y / 3 = (12 - 5x) / 3
combine like terms to get:
y = (12 - 5x) / 3
did you do this correctly?
here's a way to check.
you now have two equations.
they are:
5x + 3y = 12
y = (12 - 5x) / 3
replace y in the first equation with (12 - 5x) / 3 from the second equation to get:
first equation becomes 5x + 3 * (12 - 5x) / 3 = 12
simplify to get 5x + 12 - 5x = 12
combine like terms to get 12 = 12.
this is a true statement indicating that the two equations are identical.
another way to check is to use the second equaiton to solve for any value of x and then replacing x and y in the first equation to see if it is true.
for example, when x = 25, y = (12 - 5x) / 3 becomes y = - 113 / 3.
replace x with 25 and y with -113 / 3 in the first equation to get:
5x + 3y = 12 becomes 5 * 25 + 3 * -113 / 3 = 12 which becomes 125 - 113 = 12 which becomes 12 = 12.
since this is a true statement, the values of x and y are good.
if need some help on solving equations, try these tutorials.
http://www.mathplanet.com/education/pre-algebra/inequalities-and-one-step-equations/different-ways-to-solve-equations
https://www.mathsisfun.com/algebra/equations-solving.html
https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=how%20to%20solve%20equations%20purple%20math
lots more tutorials on the web.
a key ingredient in solving equations is moving variables from one side of the equation to the other so that the variable you want to solved for is on one side of the equation and everything else is on the other side of the equations.
the key concept is that whatever you do to one side of an equation, you have to do to the other side of the equation in order to preserve the equality.
this allows you to move terms from one side of the equation to the other in order to isolate the variable you want to solve for on one side of the equation and everything else on the other side of the equation.
some examples of what you can do to preserve the equality.
5 = 5 is the given equality.
5 + 7 = 5 + 7 becomes 12 = 12
5 - 7 = 5 - 7 becomes -2 = -2
5 * 3 = 5 * 3 becomes 15 = 15
5^2 = 5^2 becomes 25 = 25
25 = 25 is the equality.
sqrt(25) = sqrt(25) becomes 5 = 5
in all of these the equality has been preserved.
let's say you have an equation that says x + y + z = 15
solve for z
you do that by subtracting x and y from both sides of the equation.
you will get z = 15 - x - y
you just solved for z.
here's another tutorial you might like.
http://www.mathplanet.com/education/pre-algebra/more-about-equation-and-inequalities/fundamentals-in-solving-equations-in-one-or-more-steps
one more for the road:
http://www.virtualnerd.com/algebra-1/linear-equations-solve/variables-both-sides-equations/variables-both-sides-solution/variables-grouping-symbols-both-sides
this one is pretty good because it deals with expressions in parentheses which you will definitely encounter soon if you haven't already.
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