How do you solve $|- 3( x - 7) | = 21$ ?

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Answer 1 · 2018-04-12T01:49:17

$x = 0$ and $x = 14$

Because $|21| = |-21| = 21$ , we can remove the absolute value from the equation as such

$|-3(x-7)| = 21$
$-3(x-7) = +- 21$

We then have two equations (differentiated by the $+-$ sign) and we solve each using equation manipulation.

$-3(x-7) = 21$
$21 - 3x = 21$
$3x = 0 -> x = 0$

$-3(x-7) = -21$
$21 - 3x = -21$
$42 = 3x$
$x = 42/3 = 14$

Thus, our two solutions are $x = 0$ and $x = 14$ .

How do you solve |- 3( x - 7) | = 21|- 3( x - 7) | = 21?