graph/ solve
|dw:1439060839044:dw|
we have negative numbers with a relation so *we have to be careful* the "fast way" is multiply both sides by -1 and *switch the relation operator* the slow (but easy to do) way is add +3 to both sides then add +3 | x-5| to both sides either way, what do you get?
0
/x-5/<1
do it in steps -3 | x-5| < -3 which way do you want to do it? fast way or slow way?
fast way of course!
fast way: multiply both sides by -1 *flip the relation operator*
would it be 3/x-5/<3 ??
you did step 1 ok. but step 2 means you change < to > or if you had > you would change it to < or \(\le\) would be changed to \( \ge\) that is the "flip" part
3/x-5/>3
yes. the problem with the fast way is you have to remember to flip the operator... if you don't have a good memory for "details", the slow way is safer (one less rule to remember) so now you have 3 | x-5| > 3 it is safe to divide both sides by 3. you get | x-5 | > 1
with absolute value problems we *always* have two conditions either x-5 is positive , in which case , drop the | | or x-5 is negative, in which case we replace the | | with -1*(x-5)
let's do the x-5 is positive condition. we have x-5 > 1 now add +5 to both sides
x>6
now do the x-5 is negative case. can you do that one?
yes(hopefully)! So i got x<4
looks good. x<4 or x>6 are the solutions put an open circle at 4. the open (not solid , filled in) means 4 is not part of the answer, but we can get as close to 4 as we want (without being exactly 4) and x smaller than 4. all numbers smaller (to the left) of 4 are part of the solution as it would take a long time to draw a line showing all of the numbers, we use an arrow tip to show the answer includes all numbers the arrow points towards.
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