WholeLottaLove
I just wanted to make sure the way I solved this problem is correct:
What is the value of x?
1. |6-3x|=x-2
2. |5x+3|=2x+9
1. 6-3x is positive when x<2. For example, if x=1 then 6-3x = 6-3(1) = 3. 6-3x is negative when x>2. For example, if x=3 then 6-3(x) = 6-3(3) = -3.
For positive cases: 6-3x=x-2 ==> x=2
For negative cases: -6+3x=x-2 ==> x=2
My issue here is that for the positive case x must be less than 2 and for the negative case x must be greater than 2 but for both cases here, I got x =2. The answer is sufficient, but I thought that for the cases to be sufficient the results had to be in line with what x= (for example, for the positive case here, x=2 but before I found that X must be LESS than 2 for 6-3x to be positive)
Could someone explain? I see why #2 fails (because for the positive case, 2 is greater than -3/5 but for the negative case, -7/12 is NOT greater than -3/5 but I am a bit lost with #1)
Thanks!
You have a point here.
When you study a function, an abs value, you correctly define where is positive or negative
\(x>a\) positve for example
\(x<a\) negative for example
As you see the value \(a\) is not contained in neither interval... How do we solve this?
Just put an \(=\) sign under one of the above inequalities, so \(x\geq{}a\) and \(x<a\) - or \(x>a\) and \(x\leq{}a\).
Where you put the sign, it doesn not matter, the result will not change.
So just rewrite your equation into
For positive cases (\(x\leq{2}\)): 6-3x=x-2 ==> x=2
VALIDFor negative cases (\(x>2\)): -6+3x=x-2 ==> x=2
and you have the result! Nothing changes, everything you did is absolutely correct, just put an \(=\) sign in one of the intervals
Hope it's clear