SOLUTION: Please help me with this: 5x-7 < 2x+5

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Question 1209112: Please help me with this:
5x-7 < 2x+5

Found 2 solutions by ikleyn, math_tutor2020:
Answer by ikleyn(52814)   (Show Source): You can put this solution on YOUR website!
.
Please help me with this:
5x-7 < 2x+5
~~~~~~~~~~~~~~~~~~~

They want you solve this inequality 

    5x - 7 < 2x + 5.


Apply a standard procedure solving linear inequality.


Add 7 to both sides of the inequality.  You will get an equivalent inequality

    5x - 7 + 7 < 2x + 5 + 7.


Combine like terms in both sides

    5x < 2x + 12.


Now subtract 2x from both sides.  You will get an equivalent inequality

    5x - 2x < 2x + 12 - 2x.


Combine like terms in both sides

    3x < 12.


Divide both sides by 3.  You will get an equivalent inequality

    x < 4.


This last inequality determines the solution set, which is all rel numbers that are less than 4.


ANSWER.  The solution set is  {x < 4}, i.e. all real numbers that are less than 4.

         In the interval form, the solution is  (,).

Solved.

-----------------------

The standard solution procedure of solving such inequalities is collecting the terms with the unknown
in one side of the inequality and collecting constant terms in the other side;
then combining the like terms in each side and expressing the unknown variable in form of inequality.


If you want to see other examples on solving similar inequalities,  look into the lesson
    - Solving simple and simplest linear inequalities
in this site.

Learn the subject from there.



Answer by math_tutor2020(3817)   (Show Source): You can put this solution on YOUR website!

5x-7 < 2x+5
5x-2x < 5+7
3x < 12
x < 12/3
x < 4

To solve what is shown above, we get all the x terms to one side while everything else is to the other side.
When we divide both sides by a positive number, it does not flip the inequality sign.

x < 4 in interval notation is (-infinity, 4)
You can think of x < 4 as -infinity < x < 4
Replace the word "infinity" with the symbol if needed.

The graph of x < 4 on a number line has an open hole at 4 and shading to the left.
This is to visually represent all numbers smaller than 4.
The open hole means "exclude this endpoint from the solution set".

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