## anonymous one year ago Quadratic Formulas - 10 questions tried 6 times and failed epically. just don't get it. 1) When the sum of 5 and twice a positive number is subtracted from the square of the number, 0 results. Find the number. 2) 2/5x^2 -x+ 19/15 =0 3) .6x^2 = 1.2x +0.6 4) A rule for estimating the number of board feet of lumber that can be cut from a log depends on the diameter of the log. To find the diameter required to get 121 board ft of lumber, the equation (d-4/4)^2 = 121. are both answers reasonable? 5) 9x^2 -7x -5=0 6) 5x^2 - 2x +13 = 18x +1 7) 6p^2 = -19p -3 8) 5x^2 = -20x

1. anonymous

9) I can do this one :) 10) 5x^2 = 3 +2x

2. hybrik

Do you know the quadratic formula?

3. anonymous

ax2 + bx +c = 0

4. anonymous

x^2

5. hybrik

You have to put it in that form for the quadratic formula.

6. anonymous

I did 8&9

7. anonymous

oh the x = -b (sqrt b-4(a)(c))/ 2(a)

8. hybrik

Yes, $x =\frac{ -b \pm \sqrt{b^2-4ac} }{ 2a}$

9. hybrik

you have to plug in the points.

10. hybrik

Try #1.

11. anonymous

x^2 + 2x+5=0 ?

12. hybrik

To do this, you can plug in the points to get:

13. hybrik

wait keep in mind if it is just x^2, the value is 1

14. hybrik

Okay so you would have $x=\frac{ -2\pm \sqrt{(2)^2-4(1)(5)} }{ 2(1) }$

15. anonymous

I gtg, will be on tomorrow can you help then?

16. anonymous

no available computer till tomorrow

17. hybrik

Okay.

18. anonymous

Thank You so much. Very appreciated

19. hybrik

20. anonymous

um...so did you still want to help me? lol

21. pooja195

Can you make a post for each question so its easier to help? .-.

22. anonymous

I mean, yeah I can lol.

23. pooja195

Thanks :3