Let's start with definition of absolute value
1. l a
l = a , if a ≥ 0 (if "a" is positive or 0) , for example
l 5
l = 5
2. l a
l = a , if a < 0 (if "a" is negative) , for example
l 5
l =  (5) = 5
So, absolute value is always positive or zero.
So, we need to consider two cases, because expression contain variable and can be positive, or negative
1. Let's assume that (5t  7) ≥ 0 , then 5t  7 = 11 > 5t = 18 > t_{1} = 18/5
2. If (5t  7) < 0 , then we have to put the "–" before (5t  7)
– (5t  7) = 11 or we can write 5t  7 = 11 > 5t = 4 > t_{2} =  4/5
Now let's check our answer l 5 · (18/5)  7 l = 11
11 = 11
l 5 · (4/5)  7
l = 11
11 = 11
3/22/2013

Nataliya D.
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