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Mathematics 12 Online
OpenStudy (anonymous):

Help!!!!

OpenStudy (anonymous):

\[x^{2} \ge 17\]

OpenStudy (mertsj):

\[x^2-17\ge0\]

OpenStudy (mertsj):

\[(x-\sqrt{17})(x+\sqrt{17})\ge0\]

OpenStudy (mertsj):

Can you take it from there?

OpenStudy (anonymous):

Can you help me go through it please. I'm having difficulty w/ problems like this :(

OpenStudy (mertsj):

For the product to be greater than 0, both factors have to be positive or both factors have to be negative. Do you understand that?

OpenStudy (anonymous):

no sorry

OpenStudy (mertsj):

6(3) How many factors is that?

OpenStudy (anonymous):

2

OpenStudy (mertsj):

Are they both positive?

OpenStudy (anonymous):

yes because bot numbers are positie

OpenStudy (anonymous):

positive

OpenStudy (mertsj):

Is the answer positive or negative?

OpenStudy (anonymous):

positive

OpenStudy (mertsj):

So I could write that : \[6(3)\ge 0\]

OpenStudy (mertsj):

Would you agree?

OpenStudy (anonymous):

yes

OpenStudy (mertsj):

Also if both of my factors are negative as in (-6)(-3)

OpenStudy (mertsj):

I would again get a positive answer and could write that: \[(-6)(-3)\ge0\]

OpenStudy (mertsj):

However is one factor is negative and one positive as in: (-6)(3) or (6)(-3) then I could not truthfully write: \[(-6)(3)\ge0\]

OpenStudy (mertsj):

So back to your problem. If \[(x-\sqrt{17})(x+\sqrt{17}\ge0\]

OpenStudy (mertsj):

If that is true then both factors have to be negative or both factors have to be positive. Do you see that now?

OpenStudy (anonymous):

kinda. so the answer should be \[\times \ge 17\]

OpenStudy (mertsj):

So the usual technique is to draw a picture of each factor indicating where each is positive and each is negative.

OpenStudy (mertsj):

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