# Thread: Old guy helping daughter

1. ## Old guy helping daughter

We have no book and I am trying to go through example problems. I probably need to get a book and learn this all over again. 50 years old no and not done this since 20 years old.

2xsquared-8x+2=0

(2x-2)(1x-1) gets me 4x in the middle when I multiply it through.

Is this the right way to approach this, did I do something silly?

2. Originally Posted by jonb
We have no book and I am trying to go through example problems. I probably need to get a book and learn this all over again. 50 years old no and not done this since 20 years old.

2xsquared-8x+2=0

(2x-2)(1x-1) gets me 4x in the middle when I multiply it through.

Is this the right way to approach this, did I do something silly?
Since your factoring. I would think that you would factor a 2 out of the whole problem. I don't know what would go into 1 and add up to -4 though. So my post is basically useless.

Factor out a 2(x^2-4x+1)

3. Originally Posted by Matrim
Since your factoring. I would think that you would factor a 2 out of the whole problem. I don't know what would go into 1 and add up to -4 though. So my post is basically useless.

Factor out a 2(x^2-4x+1)
That's because nothing does. You can tell if a quadratic has integer factors by looking at the discriminant, $\Delta$

$$\Delta = b^2-4ac = 16-(4)(1)(1) = 12$$. As 12 is not a square number this does not have integer factors and your factorisation is as far as it goes although the 2 can be cancelled

4. Got it.

Can anyone recommend a book to relearn all of this?

Thanks

5. Originally Posted by jonb
Got it.

Can anyone recommend a book to relearn all of this?

Thanks
Perhaps Amazon.com: Engineering Mathematics (9780831133276): K. A. Stroud, Dexter J. Booth: Books