Ok I need help with questions like this one, I have a test tomorrow, and I really need someone to help me understand it better.
8n -(n - 3)=9
the answer is n=6/7, but I need someone to explain. HELP!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
2007-09-24 09:30:15 · 7 answers · asked by personalchefgurl 2 in Science & Mathematics ➔ Mathematics
8n - n + 3 = 9 (Distribute the - in the parenthesis)
7n + 3 = 9 (add the like terms)
7n = 9 - 3 (subtract 3 from both sides)
7n = 6
n = 6/7 (divide both sides by 7)
2007-09-24 09:39:43 · answer #1 · answered by Justin M 4 · 0⤊ 0⤋
Look at the problem:
8n - (n - 3) = 9
The negative sign just outside of the parentheses means that we want to subtract what's inside of the parentheses. If we want to pull things out of the parentheses, we have to switch their signs to reflect that they are supposed to be subtracted.
8n - n + 3 = 9
Notice the n switched signs (from positive to negative) and the 3 did as well (from negative to positive). Now we can start applying some reduction techniques.
Subtracting 3 from both sides of the equation:
8n - n (+ 3 - 3) = (9 - 3)
We reduce what's in the parentheses:
8n - n = 6
And since 8n - n = 7n
7n = 6
Well, if 7n = 6, and we divide both sides by 7, we get:
7n/7 = 6/7
n = 6/7
That's all, folks!
2007-09-24 16:42:00 · answer #2 · answered by Bahooya 2 · 0⤊ 0⤋
8n - (n-3) = 9 is the same as
8n - n + 3 = 9 (it helps if u put in numbers - eg 6 - (3-2) is 6 - 1 which is 5, and 6 - 3 + 2 = 5.
So now you put "like" terms together. Subtract 3 from both sides:
8n - n = 6
--> 7n = 6
Divide both by 7
--> n= 6/7
Hope u understand.
2007-09-24 16:39:56 · answer #3 · answered by Razzledazzle010 2 · 0⤊ 0⤋
First step is to get rid of the ( ), so you distribute the minus sign that is in front of the ( ). So a negative times n = -n, and a negative times -3 = 3. So now you have 8n-n+3=9. Then, subtract the 8n from n, which gives you 7n. Now you have 7n+3=9. Next, subtract 3 from both sides of the equation to get the n by itself. Now you have 7n=6. Then divide each side by 7, which gives you n=6/7.
This is how I do it:
8n -(n-3)=9
8n-n+3=9
7n+3=9
7n=6
n=6/7
2007-09-24 16:39:35 · answer #4 · answered by phoenix 1 · 0⤊ 0⤋
OK.
8n - (n - 3) = 9 Now get rid of the parenthesis by doing the indicated multiplication of everything inside by -1
8n - n + 3 = 9 Now subtract 3 from each side
8n - n = 6 Now subtract n from 8n
7n = 6 Now divide both sides by 7 to get
n = 6/7
You really --really-- need to study algebrais manipulation. It's kinda at the heart of algebra. Being able to manipulate abstract symbols as if they were actual numbers is about the only way to solve a lot of problems.
Doug
2007-09-24 16:40:37 · answer #5 · answered by doug_donaghue 7 · 0⤊ 0⤋
Step by step...
8n -(n - 3) = 9
8n - n + 3 = 9
7n + 3 = 9
7n = 6
n = 6/7
2007-09-24 16:38:29 · answer #6 · answered by J D 5 · 1⤊ 0⤋
use the distributive property.....distribute the negative into the numbers in the parenthesis and use the order of operations
2007-09-24 16:38:42 · answer #7 · answered by Vampyre Chan =] 2 · 0⤊ 0⤋