Posted on 09/27/2010 6:56:57 PM PDT by pandemoniumreigns
Long time since I’ve done much algebra...
Tried to substitute A, B, and C into
(-b +/- sqrt(b^2-4ac))/2a without writing down the terms
Idiot, stupid math mistake
Grumble Grumble
An I used to tuter Calculas in College
Never made anything but an A in any Math Class
Now I feel like mush for brains
The instructions said to use the quadratic formula.
10/(2*1) ± √[(-10)2 - (4 * 1 * (-10))]/(2 * 1)
5 ± 2√[15]
There's the problem. The 9th Circuit Court recently overturned the AC rule. It was making life difficult for too many students.
Seriously. They really did.
Okay, maybe not so much. LOL
10/(2*1) ± √[(-10)2 - (4 * 1 * (-10))]/(2 * 1)
5 ± 2√[35]
Thing is that she keeps getting the same answer that is being offered here, but her on-line test keeps saying WRONG....
so I just had to ask...
http://www.khanacademy.org/
Cheers!
'hack
It is good to know how to run the formula and plug in the values and solve it.
However, further down the line, bear in mind that the answers to the questions are never rational. They will always whole numbers. Once armed with this little nugget, it makes doing the work much easier. Once you finish the problem, look at your answer. If it is a whole number, then you are correct.
Also, have your student do ALL of he problems, not just the ones assigned. The teachers are essentially lazy, and they want to check the answers quickly. They will take their test questions right from the textbook, from the unassigned problems to see who is doing the work and who is just doing the minimum. They will have seen the format of the problem before, if not the question verbatim, and will be able to solve them more quickly. This applies to math and science as well.
It’s slightly less than 10.9
It’s easy once you recognize that no two vertical lines are parallel.
Did you get enough different answers and scoldings on this thread? Shame on them. Ignore it. Unless you have a career where you use Algebra etc. who the hell remembers that crap? most useless classes in high school and college. I haven’t used it once since I got my Master’s degree.. NOT ONCE unless I was helping my kids with their homework.
Take the correct answer and figure out what question it answers that looks sorta like the published question(problem).
Then sue them for making you learn the lesson inside and out.
Agreed...Post #19 is correct according to my sister who taught math for 27 years!!
Check: x = 5 + √35
10 + 10(5 + √35) - (5 + √35)2 = 0
10 + 50 + 10√35 - (25 + 10√35 + 35) = 0
60 + 10√35 - (60 + 10√35) = 0
60 + 10√35 - 60 -10√35 = 0
0 = 0
Check: x = 5 - √35
10 + 10(5 - √35) - (5 - √35)2 = 0
10 + 50 - 10√35 - (25 - 10√35 + 35) = 0
60 - 10√35 - (60 - 10√35) = 0
60 - 10√35 - 60 + 10√35 = 0
0 = 0
I am well aware that you have to be rather thick skinned to post a math vanity here but I think I got the answer that I needed.
The test seems to have the wrong answer...
And it's true...who needs this crap?
you can also use that logic to prove 1= -1
1=1
1=1*1
1=1^2
1=sqrt(1^1)
1=sqrt(1) * sqrt(1)
...
1=(-1)^2
1=sqrt((-1)^2)
1=sqrt(-1) * sqrt(-1)
1=i * i
1=i^2
1=-1
Find X? I can’t even find my slide rule!!!
x = 5 +/- sqrt(35) = approx 10.92 or -.92
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