## Renee99 Group Title How can you tell when a quadratic equation has no real solutions? A. when the radicand is negative B. when b in the quadratic formula is greater than the radicand C. when the radicand equals zero D. when the radicand is not a perfect square I believe the answer is A? is that right? 2 years ago 2 years ago

1. Mertsj Group Title

A

2. campbell_st Group Title

its A using the discriminant $b^2 - 4ac$ < 0 no real solutions the radical will be negative

3. experimentX Group Title

4. experimentX Group Title

i go with campbell

5. campbell_st Group Title

the square root symbol

6. Mertsj Group Title

b^2-4ac

7. Mertsj Group Title

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

8. Renee99 Group Title

Thanks!! :) I also have this one... For which value of x does the graph of y = 2x2 − 7x + 6 cross the x-axis? A. −3/2 B. −2/3 C. 2 D. 3 I think its C.

9. Mertsj Group Title

$b^2-4ac$ is the discriminant

10. Mertsj Group Title

You are correct.

11. campbell_st Group Title

you can substitute each value to find y = 0 or factorise (2x - 3)(x - 2) = 0 x = 3/2 and 2

12. Renee99 Group Title

Thanks so much, here's another one i'm stuck on... What are the approximate solutions of 4x2 + 3 = −12x to the nearest hundredth? A. x ≈ −3.23 and x ≈ 0.23 B. x ≈ −2.72 and x ≈ −0.28 C. x ≈ 0.28 and x ≈ 2.72 D. x ≈ −0.23 and x ≈ 3.23 I think its C, but I'm not sure??

13. campbell_st Group Title

put it in standard form 4x^2 + 12x + 3 = 0 use the general quadratic formula $x = (-b \pm \sqrt{b^2 - 4ac})/2a$ in your question a = 4, b = 12 and c = 3

14. Mertsj Group Title

C is correct.

15. Renee99 Group Title

thanks so much!! :)

16. Mertsj Group Title

No. It's B

17. Mertsj Group Title

Both roots are negative.

18. Renee99 Group Title

B? Really? are you sure?

19. Renee99 Group Title

Okay, i'll trust you! :)

20. Mertsj Group Title

$x=\frac{-12\pm \sqrt{96}}{8}$

21. Renee99 Group Title

I have one more question that's really confusing me, would you mind sticking around for one more?

22. Mertsj Group Title

$x=\frac{-12+9.80}{8} or x=\frac{-12-9.80}{8}$

23. Mertsj Group Title

ok

24. Renee99 Group Title

*note* don't ask me why the numbers are spreed out like that, I just copied and pasted it onto here, that how it looks on my paper. Which part of the quadratic formula tells you whether the quadratic equation can be solved by factoring? −b b2 − 4ac 2a Use the part of the quadratic formula that you chose above and find its value given the following quadratic equation: 2x2 + 7x + 3 = 0

25. Mertsj Group Title

b^2-4ac

26. Renee99 Group Title

27. Mertsj Group Title

Well which part would you choose? -b? 2a????

28. Mertsj Group Title

$b^2-4ac=7^2-4(2)(3)=49-24=25$

29. Renee99 Group Title

I don't know... This is really confusing me for some reason...

30. Renee99 Group Title

31. Renee99 Group Title

I'm still confused... :/

32. Renee99 Group Title

or is the answer this: b² - 4ac = (7)² - 4(2)(3) = 49 - 24 = 25.

33. Mertsj Group Title

The discriminant, which is b^2-4ac, is the part of the quadratic formula which tells you about the roots.

34. Mertsj Group Title

Do you understand that the question has two parts? READ THE QUESTION!!!

35. Mertsj Group Title

PART 1: Which part of the quadratic formula tells you whether the quadratic equation can be solved by factoring?

36. Mertsj Group Title

The answer to that is :b^2-4ac

37. Mertsj Group Title

PART 2: Use the part of the quadratic formula that you chose above and find its value given the following quadratic equation: 2x2 + 7x + 3 = 0

38. Mertsj Group Title

The answer to that is 25

39. Renee99 Group Title

ohhh okay, I understand now

40. Renee99 Group Title

Thank you!!

41. Mertsj Group Title

yw

42. Renee99 Group Title

I just wasn't looking at the problem correctly, sorry for the confusion and thanks again for breaking it down for me