Posted by Nicole on Friday, April 20, 2012 at 7:15pm.
Devin attempted to solve the inequality 2x+6>10 following the steps below:
â€¢subtract 6 from both sides of the inequality.
â€¢divide both sides of the inequality by 2.
He finds that x>2. Clearly explain why this is not a correct solution. In your response, be sure to explain what Devin needs to do to find the correct solution.

Algebra  Steve, Saturday, April 21, 2012 at 6:02am
multiplying or dividing by negative values changes the direction of the inequality. So, the answer is x < 2
To see why this is so, work the problem without multiplying by negative values. In this case, that can be done as follows:
2x + 6 > 10
subtract 6
2x > 4
add 2x
0 > 4 + 2x
subtract 4
4 > 2x
2 > x
see, multiplying by a negative is like swapping things to the other side and multiplying by a positive. So, the effective direction of the inequality changes.