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How to solve this equation or to get y by itself?

+1 vote
Here's the equation: x-3y=8
asked Jan 8, 2013 in PRE-ALGEBRA by payton Apprentice

2 Answers

+1 vote
given eqution is x -3y =8--------------(1)

let  x=0      x- 3y =8

   substution the eqution  (1)

                    - 3y =8

                       y = - 8/3

          ( x ,y ) =( 0, - 8/3 )

let  x= 1    substution the eqution  (1)

                     1 -3y =8

                       - 3y = 8 - 1

                          y = -7/3

          ( x ,y ) = (  1 , -7/3 )

let  x =2    substution the eqution  (1)

                   2 - 3y =8

                     - 3y =6

                         y = -2

           ( x , y ) = ( 2 , -2 )

let  x =3    substution the eqution  (1)

                   3 -3y =8

                     - 3y = 5

                       y  = -5/3

 so (x , y) = { ( 0,-8/3) ,( 1 ,- 7/3) ,( 2 ,- 2) ,( 3 ,-5/3)...............}
answered Jan 9, 2013 by krish Pupil
reshown Jan 9, 2013 by moderator
+2 votes
x-3y=8

Subtraction property of equality: if a = b then a - c = b - c. Subtract x from each side

x - 3y -x = 8 - x

Apply commutative property of addition: a + b = b  + a.

x - x  - 3y = 8 - x

Apply Additive inverse property: a + (-a) = - a + a = 0

0 - 3y = 8 - x

Apply Additive identity property: a + 0 = 0 + a = 0

-3y = 8 - x

Divide each side by -3

y = (8 -x)/-3

y = (x - 8) / 3.

i hope it helps a lil.
answered Jan 9, 2013 by Naren Answers Apprentice
you are good at math :)

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