# Thread: Square Root Problem

1. ## Square Root Problem

We are nearing the end of my algebra class.. I understand almost everything. I am currently doing a review, but I am not sure what to do for this problem..

Above the equation it says to use the discriminant to solve, but I dont believe this is a discriminant problem

Im not sure how to write it out regularly, so I will try my best.

Problem:

The square root of... 9x^2 - 12x + 4

Ive tried breaking down each # and variable seperatley but I dont understand how we are supposed to get to this answer:

Absolute Value of 3x - 2

Does anyone know what to do?

2. Originally Posted by gurrry
We are nearing the end of my algebra class.. I understand almost everything. I am currently doing a review, but I am not sure what to do for this problem..

Above the equation it says to use the discriminant to solve, but I dont believe this is a discriminant problem

Im not sure how to write it out regularly, so I will try my best.

Problem:

The square root of... 9x^2 - 12x + 4

Ive tried breaking down each # and variable seperatley but I dont understand how we are supposed to get to this answer:

Absolute Value of 3x - 2

Does anyone know what to do?
(I'll ignore the discriminant part...)

Take (3x - 2).
Square it.
(3x - 2)^2 = 9x^2 - 12x + 4, which is exactly what you have under the radical.

Now √(A^2) IS NOT (just) "A"!!!!!!!!!!!!!!!!

It is the Absolute Value of A. Some even define the absolute value in this way.

3. Originally Posted by TheChaz
(I'll ignore the discriminant part...)

Take (3x - 2).
Square it.
(3x - 2)^2 = 9x^2 - 12x + 4, which is exactly what you have under the radical.

Now √(A^2) IS NOT (just) "A"!!!!!!!!!!!!!!!!

It is the Absolute Value of A. Some even define the absolute value in this way.
So basically I just needed to factor what was underneath the radical?

4. Edit: Just to reference the discriminant part again, have you worked out the discriminant?

It's: $12^2-4(9)(4)=0$

What does that tell you about the quadratic?

5. Originally Posted by Quacky
Edit: Just to reference the discriminant part again, have you worked out the discriminant?

It's: $12^2-4(9)(4)=0$

What does that tell you about the quadratic?
It tells me that there is one rational solution because the discriminant becomes zero... but im not sure what that can do for me as far as how to get the answer...

6. Originally Posted by gurrry
It tells me that there is one rational solution because the discriminant becomes zero... but im not sure what that can do for me as far as how to get the answer...
One solution means that the quadratic is a perfect square trinomial... (ax + b)^2