# I forgot How to do these

1. Jan 20, 2008

### MrNonexistent

I forgot How to do these....

1. The problem statement, all variables and given/known data

y = x^2 - 8x + 10
change into y = (x[plus or minus]A)*(x[plus or minus]B)

I just forgot how to do these.... real fast could someone solve w/ showing work?

Thanks. I just don't remember how to do it.....

2. Jan 20, 2008

### rocomath

You need to find 2 numbers that give you the difference of -8 and the product of positive 10.

Since you won't be able to find it by simple factorization, you have to use the quadratic formula.

3. Jan 20, 2008

### MrNonexistent

Oh ok thanks.

yea, i was just running factors over and over in my head and i wasn't coming up with anything, I'm kind of brain dead, so i wasn't sure if it was just me. Thanks.

4. Jan 20, 2008

### rocomath

1 and 10
2 and 5

:(

5. Jan 20, 2008

### MrNonexistent

when i type in on Google quadratic formula, then i plug the equations in, it tells me x=16 and x = 8

?????? not the answer i need.

6. Jan 20, 2008

### MrNonexistent

also those were wrong, i did it wrong. hold on

7. Jan 20, 2008

### rocomath

Nope ... try it again.

8. Jan 20, 2008

### MrNonexistent

ok i think i got it, is it just (x - [8+$$\sqrt{24}$$/2]) * (x - [8-$$\sqrt{24}$$/2])?

9. Jan 20, 2008

### rocomath

Yes, but don't forget to reduce!

10. Jan 20, 2008

### MrNonexistent

by that, you just mean plugging it into a calculator and finding the answer, correct?

which happens to be 6.5505 & 1.4495 correct?

11. Jan 20, 2008

### rocomath

No. $$\frac{8 \pm \sqrt{4 \cdot 6}}{2}$$ can reduce.

12. Jan 20, 2008

### MrNonexistent

so 4 $$\pm \sqrt{2*3}$$?

13. Jan 20, 2008

Yeppp.