Can someone help me find the value of X?

Question

< = angle

It all equals 180 degrees.

Okay, so The answer to this problem is 9, but I keep getting 8.66666666etc.

Can someone tell me what I'm doing wrong?

m<AOB= 6x+5, m<BOC= 4x-2, m<AOC= 8x=21=180

So I know that you have to add like terms.

6x+5

+4x-2=

10x+3

+8x+21=

18x+24=180

So after you add the like terms you.

180

- 24=

156

18x=156

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

18x 18

156/18 equals 8.666666

So can someone tell me what I'm doing wrong? The back of the book says that the answer is 9, help!!!

Answer 1

Hmmm how do you have &lt;aob, &lt;boc, and &lt;aoc, wouldn&#039;t  aob+boc=aoc?

Ok, if you write the angles out then this must be true:

m&lt;AOB + m&lt;BOC = m&lt;AOC

so, just plug it in.

(6x+5) + (4x-2) = (8x+21)

10x+3=8x+21

2x=18

x=9

The way you wrote it you said that m&lt;AOC=8x+21=180.

The only possible way the line could look would be like this(with different variations of where B is but it doesn&#039;t matter):

(O is where the line B is on meets line AC,

won&#039;t let me write it in)

A

|                

|    

|_______B

|

|

C

Now no matter what the individual angles on aob and boc are you will always have aoc equaling aob+boc.

Answer 2

What IS the original equation? If its 8x-21, the the answer works out to 9, just like in the book. If it is 8x + 21, then you did it right. This may have been a typo in the book.

Answer 3

Easy.

Books like to round up to whole numbers.

8.6~ rounds up to 9.

Answer 4

You&#039;re fine up to the point where you set the two equations equal.

10x + 3 = 8x + 21

Subtract 8x from both sides:

2x + 3 = 21

Subtract 3 from both sides:

2x = 18

x = 9

At a guess:  you&#039;re going too fast, doing a lot in your head, and not writing it down.  We teachers don&#039;t insist that you write things down just to torture you.  Torturing students is just gravy.  We do it because you&#039;re less likely to make the &quot;careless&quot; or &quot;silly&quot; errors if you write everything down.  What you&#039;ve done here shows me that you do know what you&#039;re doing.  Slow down a bit and watch for the simple mistakes and you should be fine.

Edit:  Honey, how do you know they add up to 180?  By the angle addition postulate, m angle AOB + m angle BOC = m angle AOC.  Trust me on this.  Not only have I been teaching geometry since 1987, but I&#039;m also getting the answer from the back of your book.  Kinda seems I know what I&#039;m talking about, n&#039;est pas?

Answer 5

unless you copied the problem wrong the answer definately is not 9. and don&#039;t listen to the person that actually got nine ur not supposed to set the angles equal to each other ur supposed to add them all up and set it equal to 180 just like u did

Answer 6

Does the question say to round up to the nearest whole number? cause that&#039;s possbily what they&#039;ve done

don&#039;t always believe the back of the book lol trust me.

Answer 7

you wrote the problem wrong because it cant be rounded up because the answer is 9 and if you plug in 9 for all the x&#039;s it equals 186 not 180 so really its not equal to 180

Answer 8

very weird, maybe the directions tell you to round

Answer 9

You need to round it off.  So 8.66 is over 8.50 so when you round it off you get 9. Hope this helps.