6x-3y=9 solve for y

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ginny1029

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Thanks again for the help!!!!

6x - 3y = 9
-3y = 9 - 6x
-3y/-3 = (9 - 6x)/ -3 (i reduce the 9 to a 3 and the -3 to a -1)

y = -3 - 6x

does this look right to you?
 
ginny1029 said:
Thanks again for the help!!!!

6x - 3y = 9
-3y = 9 - 6x
-3y/-3 = (9 - 6x)/ -3 (i reduce the 9 to a 3 and the -3 to a -1)

y = -3 - 6x <<< You have divided (9) with (-3) - why aren't you dividing (-6) with (-3) also?

does this look right to you?
Click to expand...
 
ginny1029 said:
because in not just a 6 its 6x?
Click to expand...


I do not understand this question; is it supposed to be an answer to the question that Subhotosh asked you?

Subhotosh pointed out that you only divided one of the two terms on the righthand side by -3; you need to divide both of them.

Whenever there is more than one term in a numerator, each term gets divided by the denominator.

\(\displaystyle \frac{9 - 6x}{-3} \; = \; \frac{9}{-3} \; + \; \frac{-6x}{-3}\)

You divided the first term (the 9) by -3, but you failed to divide the second term (the -6x) by -3.

If you still don't understand your mistake, then perhaps these examples will help:

----------------

2y = 10x + 12

2y/2 = (10x + 12)/2

y = 10x/2 + 12/2

y = 5x + 6

----------------

7y = 14 - 21x

7y/7 = (14 - 21x)/7

y = 14/7 - 21x/7

y = 2 - 3x

----------------

5y = 4x - 3

5y/5 = (4x - 3)/5

y = (4/5)x - 3/5

----------------

17y = 198 + 83x

17y/17 = (198 + 83x)/17

y = 198/17 + (83/17)x

 
6x means 6(multiplied by)x

So when you divide (6x) by (3) - the (6) in (6x) gets divided by (3) and the whole thing becomes 2(multiplied by)x or 2x
 
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