## anonymous one year ago I have my answer, just want to know if the discriminant is right.. y=x^2-5x-8 y=x 2 real solutions and a discriminant of 68.

1. anonymous

Would the discriminant be 68 or 17?

2. anonymous

@Hero

3. Hero

Would you mind showing your work ?

4. anonymous

Yeah one second. I used the quadratic formula -b+-sqrt b^2 - 4ac/2a

5. Hero

Do you know what kind of problem this is you're working on?

6. anonymous

Yes. I just want to know if my answer is correct

7. anonymous

It says "use the discriminant to find the number of solutions for each system."

8. freckles

$\text{ the disciminant of } y=ax^2+bx+c \text{ is } b^2-4ac$

9. anonymous

I know

10. freckles

then how did you get two solutions?

11. freckles

discriminant will only be one number

12. anonymous

Because the answer it gives me is 6+-sqrt68/2 so I was wondering if the discriminant would be 68 or 17 once you simplify it.

13. freckles

so you didn't use the formula I wrote...

14. anonymous

I did!!

15. freckles

b^2-4ac is going to give you the discriminant

16. freckles

then how did you get + or - for the discriminant ?

17. anonymous

So it would be 68

18. freckles

D=b^2-4ac and you have a=1 b=-5 c=-8 just plug in D=(-5)^2-4(1)(-8) this shouldn't give you 68

19. anonymous

Yes it should. You set the two equations equal to each other and get x^2-6x-8=0

20. freckles

I see y=x^2-5x-8

21. anonymous

Why?

22. anonymous

Yes, but there is also the y=x

23. freckles

because I thought the question was find the discriminant of y=x^2-5x-8? Is that not the question?

24. anonymous

So once you put them equal to each other

25. anonymous

Read the entire thing. It is a system. You know with the little {

26. anonymous

{y=x^2-5x-8 {y=x

27. freckles

Oh I think you are trying to see how many solutions to the system there are I didn't understand the question because the question wasn't actually given in the title

28. anonymous

Yes....

29. anonymous

I just wanted to know if the 68 would give me 2 real solutions

30. anonymous

31. freckles

Yes replace y with x in the first equation $x=x^2-5x-8 \\ 0=x^2-6x-8 \\ a=1\\ b=-6 \\ c=-8 \\ D=b^2-4ac=(-6)^2-4(1)(-8)=36+32=68>0$ yes 68>0 so that means you have two solutions

32. anonymous

Thank you!

33. anonymous

Is what I was saying all along, but... :/

34. freckles

It might be good to post the full question in the title next time. It would be very helpful.

35. anonymous

Alright, alright.. Thank you nontheless

36. freckles

Like determine the number of solutions to the system :p

37. anonymous

*nonetheless

38. freckles

and np