Answer:
-1 ≤ x ≤ 2
Explanation:
The given equation can be rewritten as a piecewise function and solved in pieces.
The term |x+1| changes definition at x=-1. For x-values less than that, it is defined as -(x+1). Similarly, the term |x-2| changes definition at x=2. For x-values less than that, its definition is -(x-2). In the following, we consider the three pieces of the function.
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x < -1
In this domain, the absolute value functions both have negative arguments, so the equation is effectively ...
-(x +1) -(x -2) = 3
-2x +1 = 3 . . . . . . . simplify
-2x = 2 . . . . . . subtract 1
x = -1 . . . . divide by -2
This value of x is not in the domain we have defined, so there is no solution in this domain.
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-1 ≤ x ≤ 2
In this domain, the function |x+1| has a non-negative argument, but the function |x-2| has a non-positive argument. The equation is effectively ...
(x +1) -(x -2) = 3
x -x +1 +2 = 3 . . . . . eliminate parentheses, group like terms
3 = 3 . . . . . . . . . true for the entire domain
The solution here is -1 ≤ x ≤ 2.
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2 < x
Both absolute value terms have positive arguments in this domain, so the equation is effectlvely ...
(x +1) +(x -2) = 3
2x -1 = 3 . . . . . simplify
2x = 4 . . . . add 1
x = 2 . . . . divide by 2
This value of x is not in the domain we have defined, so there is no solution in this domain.
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The solution to the given equation is -1 ≤ x ≤ 2.