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January 19th, 2017, 02:35 PM   #1
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quadratic formula...But this time with a negative

says some thing about an I ?
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January 19th, 2017, 02:40 PM   #2
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At this point now
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January 19th, 2017, 02:48 PM   #3
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now here and stuck.
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January 19th, 2017, 03:17 PM   #4
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Quote:
Originally Posted by GIjoefan1976 View Post
now here and stuck.
I don't know how they expect you to do these if you haven't been taught at least rudimentary complex numbers.

There exists a number generally called $i$

which is defined such that

$i^2 = -1$

so when you see something like $\sqrt{-444}$

this is $\sqrt{i^2 444} = i\sqrt{444}$

$i$ is the unit imaginary number, similar to the way $1$ is the unit real number.

The complex numbers are all numbers of the form $a + i b, ~a, b \in \mathbb{R}$
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January 19th, 2017, 03:55 PM   #5
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Ya gotta be more careful, Joe me boy!

Given equation is: (a - 8 )(a - 2) = -1
Simplifies to:
a^2 - 10a + 16 = -1
Continue...
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January 19th, 2017, 04:30 PM   #6
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$a^2-10a+17 = 0$

quadratic formula $a=1$, not $8$
$b=-10$ and $c=17$

$b^2-4ac = 100 - 4(1)(17) = 32$

now finish it ... you've been your own worst enemy by not paying attention to detail.
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January 19th, 2017, 09:36 PM   #7
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Quote:
Originally Posted by romsek View Post
I don't know how they expect you to do these if you haven't been taught at least rudimentary complex numbers.

There exists a number generally called $i$

which is defined such that

$i^2 = -1$

so when you see something like $\sqrt{-444}$

this is $\sqrt{i^2 444} = i\sqrt{444}$

$i$ is the unit imaginary number, similar to the way $1$ is the unit real number.

The complex numbers are all numbers of the form $a + i b, ~a, b \in \mathbb{R}$
Thanks for sharing and teaching me this, it will be for sure something I will pass on to my tutors!
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January 19th, 2017, 09:56 PM   #8
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Originally Posted by GIjoefan1976 View Post
Thanks for sharing and teaching me this, it will be for sure something I will pass on to my tutors!
that's all well and good but the point a couple others have made is that you wouldn't have run into this if you hadn't messed up the algebra.

So it makes more sense that you hadn't seen complex numbers yet.

You'd have seen them eventually.
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January 25th, 2017, 10:14 AM   #9
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Quote:
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that's all well and good but the point a couple others have made is that you wouldn't have run into this if you hadn't messed up the algebra.

So it makes more sense that you hadn't seen complex numbers yet.

You'd have seen them eventually.
Thanks Yes I still make mistakes but the video that was given to me by My math class said I would be dealing with a negative so When i got what was above I thought I had gotten the situation I was meant to get.
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January 25th, 2017, 04:04 PM   #10
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Your basic problem, GIJoefan1986, is that you multiplied (x- 8 )(x- 2) and got rather than ! Where in the world did that come from?
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