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6*(x-5)-2*(4x+2) ≥ 80, in the numeric set Z (sorry if not right), the result i got was x ≥ -57, it should be write {-57,-58,-59,...} or {...,-59, -58, -57}? And why?  

 Jul 9, 2017
 #1
avatar+128079 
+1

 

Actually, the solution  is

 

x ≤ - 57

 

You can write your solution as

 

( - ∞ , -57 ]      

 

The bracket shows that the number to its left is included in the solution...infinities are never bracketed but are shown with a parentheses beside them

 

 

 

cool cool cool

 Jul 9, 2017
 #2
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0

thanks, but could you write the process to the result for me? im more confused than a blind man in a shooting.

Guest Jul 9, 2017
 #3
avatar+128079 
+1

 

6*(x-5)-2*(4x+2) ≥ 80     simplify

 

6x - 30 - 8x - 4  ≥ 80      combine like terms on the left

 

-2x - 34  ≥ 80      add 34 to both sides

 

-2x  ≥  114          

 

divide both sides by -2......don't forget to reverse the inequality sign as we do in an inequality when we  divide or multiply by a negative  !!!

 

x ≤ - 57

 

 

cool cool cool

 Jul 10, 2017
edited by CPhill  Jul 10, 2017
 #4
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Thank you very much man, you answered my two questions on this site and even explained it, man you helped me a lot, thank you very much, really, thank you.

Guest Jul 10, 2017

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