# solving inequalities

• Feb 15th 2010, 05:38 PM
justahengin87
solving inequalities
when solving an inequality and you have to take the square root of both sides, what is the rule for the changing of the inequality sign?

if the number was between 0 and 1, then the sign would need changing, but if it were greater than 1, it wouldnt

same goes for 0 and -1.

for example:

-9 < 16x^2

that turns into: 3i < 4x
but im unsure because the rules would differ for the above mentioned numbers.

helppp
• Feb 15th 2010, 05:42 PM
Prove It
Quote:

Originally Posted by justahengin87
when solving an inequality and you have to take the square root of both sides, what is the rule for the changing of the inequality sign?

if the number was between 0 and 1, then the sign would need changing, but if it were greater than 1, it wouldnt

same goes for 0 and -1.

for example:

-9 < 16x^2

that turns into: 3i < 4x
but im unsure because the rules would differ for the above mentioned numbers.

helppp

This doesn't make any sense since complex numbers can't be ordered...
• Feb 15th 2010, 05:58 PM
justahengin87
bad example, but what is the ruling?
• Feb 15th 2010, 06:06 PM
Prove It
Quote:

Originally Posted by justahengin87
when solving an inequality and you have to take the square root of both sides, what is the rule for the changing of the inequality sign?

if the number was between 0 and 1, then the sign would need changing, but if it were greater than 1, it wouldnt

same goes for 0 and -1.

for example:

-9 < 16x^2

that turns into: 3i < 4x
but im unsure because the rules would differ for the above mentioned numbers.

helppp

If you are taking the square root of both sides of an inequality, you have to make use of the fact that $\displaystyle \sqrt{x^2} = |x|$.