## Swageraid32 Group Title @tcarroll010 can you help me with 4 and 5 of this.... one year ago one year ago

1. Swageraid32 Group Title

2. Swageraid32 Group Title

those are my last two please........... ;/

3. jim_thompson5910 Group Title

# 4 D = b^2 - 4ac D = (1)^2 - 4(0.05)(1) D = ???

4. shyLove98 Group Title

I'm sorry. I don't know any of this. I tried. I'm really really really sorry. :(((

5. phi Group Title

if you have a the equation of a parabola in standard form: y= ax^2 + bx +c you match up the coefficients of your equation with a, b, and c then use those numbers for a, b, and c in the formula discriminant= b^2 -4ac jim_t already did most of the work for you.

6. Beautiful_Lier96 Group Title

im confused

7. phi Group Title

y= 0.05 x^2 + 1x + 1 is your equation

8. evergirl Group Title

I think phi has got you covered

9. Swageraid32 Group Title

hmmm....???

10. Swageraid32 Group Title

you mean that is how i do the quadratic part??

11. phi Group Title

we are doing question 4. They want to know the discriminant (of your quadratic equation) I assume they mean the equation they give in question 1 To find the discriminant we first do step 1: first step: pattern match y= 0.05 x^2 + 1x + 1 y= a x^2 +b x + c what is a,b, and c?

12. Swageraid32 Group Title

i have that part i need number 5

13. phi Group Title

what did you get for a, b and c

14. Swageraid32 Group Title

wait what?? like for the explanation part??

15. Swageraid32 Group Title

D = (1)^2 - 4(0.05)(1)

16. Swageraid32 Group Title

??

17. phi Group Title

I see you copied Jim's answer To find the discriminant we first do step 1: first step: pattern match y= 0.05 x^2 + 1x + 1 y= a x^2 +b x + c what is a,b, and c?

18. Swageraid32 Group Title

a=0.05 b=1x c=1

19. phi Group Title

almost, b is just 1 (we only want the numbers. a= 0.05, b=1 , c=1 step 2: replace the letters a, b, and c in b^2 - 4ab with the numbers you just found (remember b^2 is short for b*b 4ab is short for 4*a*b * means multiply

20. Swageraid32 Group Title

1^2-4(0.05)(1)

21. Swageraid32 Group Title

.8

22. phi Group Title

now what is 1^2 ? 1*1 = 1 4*0.05 is 0.2 0.2*1 is 0.2 so 1- .2 = 0.8 the discriminant is 0.8

23. Swageraid32 Group Title

ok i get that thanks for actually working with me and not giving just the answer :D

24. Swageraid32 Group Title

so could you assist me in #5 as well??

25. Swageraid32 Group Title

@phi ??

26. phi Group Title

For 5, the quadratic formula is $x=\frac{−b±\sqrt{b^2−4ac}}{2a}$ notice that the stuff inside the square root is the "discriminant", which you already figured out is 0.8 you also know what a, b and c are. So replace the letters with numbers what do you get?

27. Swageraid32 Group Title

a=0.05, b=1, c=1 $x=\frac{−1±\sqrt{1^2- 4\times0.05\times1}}{2\times0.05}$

28. Swageraid32 Group Title

@phi ?? like that??

29. phi Group Title

I just noticed that the equation you have from question 1 should be y= 0.05x^2 -x +1 notice that b is -1 (not +1) this changes your answers (gack!)

30. Swageraid32 Group Title

yea i know it is a typo the graph is wrong

31. phi Group Title

if we use b= -1 we get $x= \frac{1 ± \sqrt{0.8}}{0.1}= 10±\sqrt{80} = 10± 4\sqrt{5}$ you get two answers x= 10+4sqrt(5) and x= 10-4sqrt(5) these are where the graph crosses the x-axis

32. Swageraid32 Group Title

wait i am confused

33. phi Group Title

which part?

34. Swageraid32 Group Title

the part like so i need to switch it to a -1?

35. phi Group Title

It's your call. The question says find the equation, from the graph. Did you find the equation from the graph? If so, you got it wrong?

36. Swageraid32 Group Title

o wow no i used the graph that was provided on the graph ;( that means i have to go back and do this all again :/

37. phi Group Title

Q1 general equation is y=0.05 x^2 -x +1 vertex form is 0.05(x-10)^2 - 4

38. Swageraid32 Group Title

so that means its this? y= 0.05 x^2 -1x + 1

39. phi Group Title

in Q2, the -10 become +10 so that means its this? y= 0.05 x^2 -1x + 1 Yes

40. phi Group Title

in Q2, the domain are all valid x's in this case, -inf to +infinity

41. phi Group Title

in Q2, the range is all y values. from the graph, you see y is always bigger than -4

42. phi Group Title

in Q3, your x-intercepts should be positive

43. phi Group Title

in Q4, b is -1 not +1, but it won't change the discriminant calculation.

44. Swageraid32 Group Title

ok thanks for all that :D

45. Swageraid32 Group Title

i do need your help again though i mean how are you supposed to find the domain and range? @phi

46. Swageraid32 Group Title

@phi