Question:

I need help with solving inequalities?

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I need help on these following problems and how to graph them:

1) |x+1| ≥ 1.5

2) |-4 - (y-5)| - 3 > -1

For these questions, I need to answer and verify whether if it is true for all real numbers or has no solution:

1) -4 ≤ -1/2 - 2y ≤ 3/2

2) x+11 < -1 or -1/2x ≤ -4

3) -(8+m) < 8 - m

4) -3 -1/2t > 3 or 7.5 (1 - 8t) ≥ 63t

5) 2y + 3 < 4y - 1 ≤ 3 (y+1)

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2 ANSWERS


  1. 1) lx+1l ≥ 1.5  =&gt;  -1.5 ≥ x+1 or x+1 ≥ 1.5

    So, it&#039;s -2.5 ≥ x or x ≥ 0.5

    2) |-4 - (y-5)| - 3 &gt; -1  =&gt;  |-4 - (y-5)| &gt; 2  =&gt;  l1-yl &gt; 2

    So, same as the first one. l1-yl &gt; 2  =&gt;  1 &gt; y or y &gt; 3

    It&#039;s 1 &gt; y or y &gt; 3


  2. When an inequality has an absolute value, you rewrite it as 2 inequalities.

    1) |x+1| ≥ 1.5

    x + 1 ≥ 1.5

    x ≥ .5

    -(x + 1) ≥ 1.5

    -x - 1 ≥ 1.5

    -x ≥ 2.5

    x ≤ -2.5

    To graph, draw circles above -2.5 and .5, fill in the circles. Draw a line from the circle above -2.5 going to the left. Draw a line from the circle above .5 going to the right.

    2) |-4 - (y-5)| - 3 &gt; -1

    (-4 - (y - 5)) - 3 &gt; -1

    -4 - y + 5 - 3 &gt; -1

    -y - 2 &gt; -1

    -y &gt; 1

    y &lt; -1

    -(-4 - (y - 5)) - 3 &gt; -1

    -(-4 - y + 5) - 3 &gt; -1

    4 + y - 5 - 3 &gt; -1

    y - 4 &gt; -1

    y &gt; 3

    Draw an open circle at y = -1, line going in the direction of -infinity.

    Draw an open circle at y = 3, line going in the direction of infinity.

    1) -4 ≤ -1/2 - 2y ≤ 3/2

    Separate into two equations:

    -4 ≤ -1/2 - 2y

    Multiply by 2:

    -8 ≤ -1 - 4y

    -7 ≤ -4y

    7/4 ≥ y

    -1/2 - 2y ≤ 3/2

    Multiply by 2:

    -1 - 4y ≤ 3

    -4y ≤ 4

    y ≥ 1

    Rewrite together (because they are overlapping solutions):

    1 ≤ y ≤ 7/4

    Draw filled in circles at 1 and 7/4, connect the circles with a line.

    2) x + 11 &lt; -1 or -1/2x ≤ -4

    Solve each separately:

    x + 11 &lt; -1

    x &lt; -12

    -1/2x ≤ -4

    x ≥ 8

    Since the two solutions do not overlap, do not rewrite.

    Draw an open circle at -12, line goes to the left.

    Draw a filled in circle at 8, line goes to the right.

    3) -(8 + m) &lt; 8 - m

    -8 - m &lt; 8 - m

    Add m to both sides:

    -8 &lt; 8

    True. The solution for this is ALL REAL NUMBERS.

    4) -3 -1/2t &gt; 3 or 7.5 (1 - 8t) ≥ 63t

    -3 - (1/2)t &gt; 3

    -(1/2)t &gt; 6

    t &lt; -12

    7.5(1 - 8t) ≥ 63t

    7.5 - 60t ≥ 63t

    7.5 ≥ 123t

    7.5/123 ≥ t

    Draw a filled in circle at 7.5/123 (15/246), line to the left.

    5) 2y + 3 &lt; 4y - 1 ≤ 3 (y+1)

    Separate into two inequalities:

    2y + 3 &lt; 4y - 1

    2y + 4 &lt; 4y

    4 &lt; 2y

    2 &lt; y

    4y - 1 ≤ 3(y + 1)

    4y - 1 ≤ 3y + 3

    y ≤ 4

    Since the solutions overlap, rewrite:

    2 &lt; y ≤ 4

    Draw an open circle at 2 and a filled in circle at 4. Connect the circles with a line.

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