Question:

Ix+14I+3>17 pre calc?

by Guest61887  |  earlier

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need help please. i tried to figure this out and i have no idea. the example in the book didn't help either. the answer is x<-28, x>0

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  1. okay to solve this equation first you have to isolate the variable:

    |x + 14| + 3 &gt; 17

    |x + 14| &gt; 14

    now, remember that the absolute value graph includes both positive and negative values for x; so, you have to solve for values of x that are both greater than 14 and less than -14.

    x + 14 &gt; 14, x + 14 &lt; -14

    x &gt; 0, x &lt; -28




  2. |x + 14| + 3 &gt; 17

    To solve this absolute value inequality, isolate the absolute value.

    |x + 14| &gt; 14

    Split into two inequalities.  For absolute inequalities in the form

    |z| &gt; c, then

    z &gt; c OR z &lt; -c

    And for the form

    |z| &lt; c, then

    -c &lt; z &lt; c

    We have the first form, obviously, so,

    |x + 14| &gt; 14

    becomes

    x + 14 &gt; 14

    OR

    x + 14 &lt; -14

    Solve each inequality by isolating x.

    x &gt; 0

    OR

    x &lt; -28


  3. There&#039;s more then one way to do this problem. I&#039;ll do a couple and you can choose which one you like:

    ——————————————————————————————————————

    (Option 1)

    Absolute value does one of two things:

    (a) If the contents are positive or zero, it does nothing.

    (b) If the contents are negative, it changes the sign (multiplies by negative 1).

    Possibility (a), it does nothing:

    ( x + 14 ) + 3 &gt; 17

    x + 17 &gt; 17

    x &gt; 0

    Possibility (b), it changes the sign:

    -( x + 14 ) + 3 &gt; 17

    -x - 14 + 3 &gt; 17

    -x - 11 &gt; 17

    -x &gt; 28

    Remember to change the direction of the equality when you multiply or divide by a negative number:

    -x &gt; 28

    x &lt; -28

    If you look at these on a number line, it becomes clear that they are on opposite sides of two points:

    &lt;===)----(===&gt;

    .... -28 .. 0

    As an interval, this would be:

    ( -∞, -28 ) U ( 0, ∞ )

    ——————————————————————————————————————

    (Option 2)

    Isolate the absolute value:

    | x + 14 | + 3 &gt; 17

    | x + 14 | &gt; 14

    The contents of the absolute value must have a distance from zero greater than 14.

    That means that the contents must be &gt;14 or &lt;-14

    Express this on one line:

    -14 &gt; x + 14 &gt; 14

    Solve for x:

    -14 -14 &gt; x + 14 -14 &gt; 14 - 14

    -28 &gt; x &gt; 0

    It&#039;s not &quot;squeezed&quot; between two values (less than a bigger one and greater than the smaller one), which makes this a somewhat &quot;odd&quot; inequality, but it&#039;s a bit easier to do than the other perhaps.

    Thus, you have the separate solutions:

    x &lt; -28 or x &gt; 0

    ---

    If, through either of these methods, you came up with a solutions such as:

    x &gt; -2 and x &lt; 1

    -2 &lt; x &lt; 1

    1 &gt; x &gt; -2

    As these would graph on a number line like:

    &lt;---(====)---&gt;

    .... -2 ..... 1

    You have the values confined &quot;between&quot; two values.

    Thus your answer would be:

    -2 &lt; x &lt; 1

    or in interval notation:

    (-2, 1)

  4. |x + 14| + 3 &gt; 17

    Subtract 3 from both sides

    |x + 14| &gt; 14

    Write as 2 inequalities

    x + 14 &gt; 14

    x + 14 &lt; -14

    Subtract 14 from both sides and the answer is:

    x &gt; 0

    x &lt; -28

      
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