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?

Guest Jul 9, 2017

#1**+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

CPhill
Jul 9, 2017

#3**+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

CPhill
Jul 10, 2017