Posted by cici on Wednesday, February 25, 2009 at 8:12pm.
i'm studying for a test and i've just got a few questions..
1If x^2+8x+m has one double root then m=? and the vertex is?
2I got 3i(s.r)5 / 5 for this problem> 15(s.r)125.. is that correct?
3Is the answer for (53i)^2 30i+ 16 ?
4is the answer to the formula 25x^220x+1 in simplest radical form 2+/(s.r)3/10?

math  drwls, Wednesday, February 25, 2009 at 8:24pm
1. If x^2 + 8x + m has a double root if it is a perfect square. Select a value of m that makes it one
2. Is the problem to rewrite
15  sqrt(125)?
If so, the two different expressions you wrote are not equal
3. 25 30i 9 = 30i + 16. yes
4. You have written a polynomial expression but not an equation. Expressions can be rearranged but do not have "solutions". If you are looking for the soution to
25x^2 20x +1 = 0, what you wrote is not it. The first term would be 20/50 = 2/5 
math  Reiny, Wednesday, February 25, 2009 at 8:29pm
1. if there is a double root, then the curve must touch the xaxis, and the factors must be xa)(xa), where a is the contact value on the xaxis
which means that x^2 + 8x + m must be a perfect square, looks like m has to be 16
and the xaxis contact point would be (4,0)
So what do you think about the vertex?
2. Are you simplifying 15  √125 ?
if so, then
15  √125
= 15 5√25*√1
= 15  25i
were you trying to factor that? if so, then
= 5(3 + 5i)
3. ????
4. your wording is horrible
are you asking to solve 25x^220x+1 = 0 by the quadratic formula?
then x = (20 ± √300)/50
= (20 ± 10√3)/50
= (2 ± √3)/5