# find the range of values for p inequality question

• June 24th 2013, 03:09 AM
pumbaa213
find the range of values for p inequality question
Find the range of values of p for which the equation x^2 - 6x + p^2 =0 has real roots

I got till this part :
p^2 <= 9
The answer is -3<=p<=3
How do I get that? THANK YOU!
• June 24th 2013, 03:13 AM
Plato
Re: find the range of values for p inequality question
Quote:

Originally Posted by pumbaa213
Find the range of values of p for which the equation x^2 - 6x + p^2 =0 has real roots
The answer is -3<=p<=3 How do I get that? THANK YOU!

Use the discriminate: $36-4p^2>0$ .
• June 24th 2013, 03:25 AM
pumbaa213
Re: find the range of values for p inequality question
Sorry im still unsure can you help me further? Thank you!
Why can't The answer be p<=3 OR p<= -3 ? How does it become -3<= p <= 3 ? Thank you!
• June 24th 2013, 03:34 AM
Plato
Re: find the range of values for p inequality question
Quote:

Originally Posted by pumbaa213
Sorry im still unsure can you help me further? How does it become -3<= p <= 3 ? Thank you!

It is basic algebra. You need to be able to do simple elementary algebra in order to work at this level.

Maybe you ought to speak to your instructor?
• June 24th 2013, 04:23 AM
Prove It
Re: find the range of values for p inequality question
Quote:

Originally Posted by pumbaa213
Sorry im still unsure can you help me further? Thank you!
Why can't The answer be p<=3 OR p<= -3 ? How does it become -3<= p <= 3 ? Thank you!

Think of the number 0 for example. This is \displaystyle \begin{align*} \leq 3 \end{align*}, but it's not \displaystyle \begin{align*} \leq -3 \end{align*}. How are you supposed to know which is correct?
• June 24th 2013, 07:13 AM
spacemenon
Re: find the range of values for p inequality question
p^2<=9 so p<=sqrt 9 or next part we change the sign wen we take negatve sqrt 9 so p<=3 or p>=-3

-3<=p<=3
• June 24th 2013, 10:10 PM
pumbaa213
Re: find the range of values for p inequality question
Ok I ve got it..! Thanks guys! :-)