How do you solve $abs(-2r-1)=11$ ?

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Answer 1 · 2017-10-30T17:54:09

$r = -6, r = 5$

This is an absolute value equation meaning that we need to split this into two equations; the original equation and the opposite of it:

$-2r-1 = 11$ and $-2r-1=-11$
Notice that the $11$ became $-11$ .

Now we can solve this by simplifying. Let's simplify the first one:
$-2r-1 = 11$
$-2r = 12$
$r = -6$

Second one:
$-2r-1 = -11$
$-2r = -10$
$r = 5$

Now let's check our work by plugging what we got for r back into the original equation $|-2r-1| = 11$ .
$|-2(-6) -1|= 11$
$|12-1| = 11$
$11 = 11$ :)

$|-2(5)-1|=11$
$|-10-1| = 11$
$|-11| = 11$
$11 = 11$ :)

So our two solutions are $r = -6$ and $r = 5$ .

How do you solve abs(-2r-1)=11abs(-2r-1)=11?