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what is the solution set to the inequality 12<3x-15

what is solution to the inequality 12<3x-15

a) {x:x<-1}

b) {x:x<9}

c) {x:x>-1}

d) {x:x>9} 

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Mykola V. | Math Tutor - Patient and ExperiencedMath Tutor - Patient and Experienced
4.9 4.9 (52 lesson ratings) (52)

In order to solve this inequality, we simply need to solve for x.

This case would look as follows:

12<3x-15. Add 15 to each side

12+15<3x-15+15 => 27<3x. Divide each side by 3.

27/3<3x/3 => 9<x. 

Our work is done. So what we have is any value of x greater than 9 will satisfy the inequality.

Answer: D.


I want to add that solving inequality follows the same rules as solwing equations with one exeption:

You can add the same number to both sides of inequality.

You can subtract the same number from both sides of inequality.

You can multiply or divide both sides of inequality by the same positive number.

Exeption: You can multiply or divide both sides of inequality by the same negative number but you have to swich inequality sign to the opposite.


Yes, that is a good point. I thought about explaining that. Thank you.

Elaine C. | English, Elem. Math, Pre and 1st Algebra, Vocab., Reading,English, Elem. Math, Pre and 1st Algebra...
x is 9; it is = to 9; not less and not more than 9.