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33 votes
33 votes
Solve the |4X -5|= |-X +5|

User Luzo
by
3.0k points

1 Answer

20 votes
20 votes

Recall the definition of absolute value:


|x| = \begin{cases} x &amp; \text{if } x \ge 0 \\ -x &amp; \text{if } x < 0 \end{cases}

Then we have a few cases to consider:

• If
4x-5\ge0 and
-x+5\ge0, the equation simplifies to


4x-5 = -x+5 \implies 5x=10 \implies \boxed{x=2}

• If
4x-5<0 and
-x+5\ge0, we get


-(4x-5) = -x + 5 \implies -3x = 0 \implies \boxed{x=0}

• If
4x-5\ge0 and
-x+5<0, then


4x-5 = -(-x+5) \implies 3x=0 \implies x=0

but we already have this solution.

• If
4x-5<0 and
-x+5<0, then


-(4x-5) = -(-x+5) \implies -5x = -10 \implies x=2

which we also already found.

User Fujifish
by
3.0k points
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