A typical linear equation in one variable might be ax+b=0. In similar fashion a typical linear inequality might be ax+b<0. The solution to the equation is found by subtracting "b" from both sides, then dividing both sides by "a" so that x = -b/a. The same method works the same way for the inequality if "a" is positive. That is, x < -b/a. However, if "a" is negative, the direction of the inequality must be reversed: X > -b/a.

Example: 2x-6=0 has solution x=-(-6)/2 = 3. 2x-6<0 has solution x<3.

Example showing the difference: -2x-6=0 has solution x=-3. -2x-6<0 has solution x > -(-6)/(-2), or x>-3.

When working with equations or inequalities, you can add or subtract the same thing from both sides without any problem. When working with equations or inequalities, you can multiply or divide both sides by any positive number without any problem. When working with equations, you can multiply or divide both sides by any negative number without any problem, but when you multiply or divide both sides of an inequality by some negative number, you need to reverse the sense of the inequality.

Example: 2x-6=0 has solution x=-(-6)/2 = 3. 2x-6<0 has solution x<3.

Example showing the difference: -2x-6=0 has solution x=-3. -2x-6<0 has solution x > -(-6)/(-2), or x>-3.

When working with equations or inequalities, you can add or subtract the same thing from both sides without any problem. When working with equations or inequalities, you can multiply or divide both sides by any positive number without any problem. When working with equations, you can multiply or divide both sides by any negative number without any problem, but when you multiply or divide both sides of an inequality by some negative number, you need to reverse the sense of the inequality.