math help!!!?

Question

im currently working on a math review and there are some questions that i dont know how to solve so if someone could go to the following link and help me out with #20 that would be the bestest!!!

http://www.montgomerycollege.edu/Departments/math/placement/clmtest.pdf

Answer 1

first of all you should know that l x l <10
also means that l (plus or minus) x l <10
hence
(plus or minus) x < 10
if it is +x
then
+x <10 <=> x <10 (< sign is not changed because it is +x)
if it is -x
then
-x < 10 <=> x > -10 (< sign is changed to > due to the - sign in front of x)
hence we can conclude that...
l x l < 10 <=> -10 < x < 10

so back to your question..
l 2x-8 l < 10
-10 < 2x-8 < 10
you may seperate this equation
-10 < 2x-8 and 2x-8 < 10
-10+8 < 2x and 2x < 10+8
-2 < 2x and 2x < 18
2x > -2 and x < 18/2
x > -2/2 and x < 9
x > -1 and x < 9
now we see that the answer is ( x>-1 ) AND ( x<9 )
which can be further simplified become
-1 < x < 9
the answer is (e)

Answer 2

The answer to #20 is the last option
-1 If 'x' assumes any value outside these designated limits, /2x - 8/ will always be larger than 10, which, as stated in the question, must not be the case.

PS : I'm soory about my inefficiency in recreating mod. I had to use slashes instead of straight lines.

Answer 3

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Answer 4

the absolute value problem has a negative and positive value... so start the inequality with both ....

- 10 < 2x - 8 < 10 .... reduce ...add 8

-2 < 2x < 18
........................then divide by 2

-1 < X < 9
(-1 , 9 ) over the interval between -1 and nine, all values of x satisfy the equation

Answer 5

okay, the | | bit means theat you need to use

2x - 8 < 10 and 2x - 8 < -10 and solve them

2x - 8 < 10
2x < 10 + 8
2x < 18
x < 9

and
2x - 8 < -10
2x < -10 - 8
2x < -18
x < -9

so if x < 9 and x < -9 then the answer is

b) -9 < x < 9

Answer 6

it could either be x<1 or x<-9 i hope i helped! sence it is an adsolute value you have to solve it twice the first time it looks like this......
|2x-8|<10 or
2x -8<10 then solve to equal x<9 then
2x -8<-10 then sovle to equal x<-9
i hope i am right you can also surf yahoo or google for homwork helpers

Answer 7

Is the math level so low in USA?

O mio Dio!

Answer 8

I couldn't get the link to work, sorry ...

Answer 9

State your problem specifically please