i was doing some limits graphing and i notice this. I was doing a right hand limit. How come x4 is 04-x and not x-40?

the original function is limit x-4+ 3/(4-x)^3

Question

i was doing some limits graphing and i notice this. I was doing a right hand limit. How come x>4 is 0>4-x and not x-4>0?

the original function is limit x->4+    3/(4-x)^3

myininaya · Answer

x>4 is x-4>0

myininaya · Answer

this approaches negative infinity since the top is poisitive and the bottom is negative and close to zero as x gets closer to 4

anonymous · Answer

the guide line in the book says 4-x<0

myininaya · Answer

x-4>0
-(x-4)<0
4-x<0

myininaya · Answer

whenever you multiply or divide by negative the inequality flips

amistre64 · Answer

x > 4  is just like an equation except for the fact that it isnt "equal"; but the same steps apply in solving:

x > 4   ; subtract x from both sides to get:

0 > 4-x   ;  if we flip this around the inequality flips as well:

4-x < 0  ; is the same statement

myininaya · Answer

4>2
-4<-2

anonymous · Answer

i mean how come its not x-4>0? 
i bring the 4 over instead or the x

amistre64 · Answer

it is the same

myininaya · Answer

that is true x-4>0

myininaya · Answer

-(x-4) does not equal x-4

anonymous · Answer

0>4-x$$ and \not \neq$$ x-4>0

anonymous · Answer

oops
0>4-x≠ x-4>0

amistre64 · Answer

one says:  0 < 10;  the other says  -10 < 0

anonymous · Answer

oh so its the same?

anonymous · Answer

but when i graph it in the calculator it gives off a left hand limit

amistre64 · Answer

4-x > 0    is the same as saying:  0 < -(4-x)
                                                  0 <  x-4

myininaya · Answer

|x|>0
-x<0<x (x not equal to 0)
|x-4|<0
-(x-4)<0<x-4
as long as x does not equal 4

myininaya · Answer

i think you are losing your mind lol

amistre64 · Answer

could be :)

anonymous · Answer

lol
yeah i been zooom through the algebra to cal 1 review in a week

amistre64 · Answer

it would help to know what the original problem is asking for tho ;)

anonymous · Answer

http://tutorial.math.lamar.edu/Classes/CalcI/InfiniteLimits.aspx example 4

myininaya · Answer

later guys gl losttime

anonymous · Answer

thanks though the problem got me curious, the guideline showed x>4 is 0>4-x but when i was doing it i got x-4>0 and i got curious what if they brang the 4 over and the answer was different, but yeah i'll look it over

anonymous · Answer

oh lmao right yes its the same the negative 1 will reverse the sign, silly me

anonymous · Answer

but do u understand that is just removing one of the variables away and solving for the other?