# Answer to Question #3878 in Real Analysis for junel

Question #3878

Find all x ∈ R that satisfy the equation& |x+1| + |x-2| = 7.

Expert's answer

|x+1|+|x-2|=7

Let’s estimate our x using the simple property of module:

& |x|& = { -x, x<0

& x, x>0

Imagine that we’re dividing our rational numbers into three groups: x ∈(-∞,-2),

x∈(-2,-1),& x∈(-1,+∞) we have such systems.

{x+1<0 & -x-1-x+2=7

& x-2<0) x = -3

{x+1>0 x+1-x+2=7

& x-2<0 x-∄

{x+1<0 -x-1+x-2=7

& x-2>0 & & x-∄

{x+1>0 x+1+x-2=7

& x-2>0 & x = 4

Answer: x=-3, x=4

Let’s estimate our x using the simple property of module:

& |x|& = { -x, x<0

& x, x>0

Imagine that we’re dividing our rational numbers into three groups: x ∈(-∞,-2),

x∈(-2,-1),& x∈(-1,+∞) we have such systems.

{x+1<0 & -x-1-x+2=7

& x-2<0) x = -3

{x+1>0 x+1-x+2=7

& x-2<0 x-∄

{x+1<0 -x-1+x-2=7

& x-2>0 & & x-∄

{x+1>0 x+1+x-2=7

& x-2>0 & x = 4

Answer: x=-3, x=4

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