## AriM Group Title Using the quadratic function, provide the x intercepts of x^2+4x-21 Can someone just tell me what the quadratic function is..? 11 months ago 11 months ago

1. myininaya Group Title

The quadratic function you have is x^2+4x-21 The graph will be a parabola

2. myininaya Group Title

To find the x-intercepts, set your quadratic expression(function) equal to 0. Then solve for x.

3. AriM Group Title

hmm thats what i did @myininaya and i got x = -7 and 3 but the teacher wrote -2 and use quadratic function..

4. myininaya Group Title

What is -2 suppose to be ? Your x-intercepts are correct for this quadratic function.

5. AriM Group Title

Oh im just saying he took off 2 points and wrote use quadratic function.

6. myininaya Group Title

Does he mean formula?

7. myininaya Group Title

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

8. AriM Group Title

hmm ill try it.

9. AriM Group Title

10. myininaya Group Title

Np. Good luck.

11. AriM Group Title

tnx

12. AriM Group Title

oh if you do the quadratic function you get 3 and -7. Can you check that for me? @myininaya

13. AriM Group Title

actually, never mind. I see his point but you could have just done (x+7) (x-3) and gotten the intercepts that way.

14. AriM Group Title

do you write it as (3,0) and (-7,0) though?

15. myininaya Group Title

Yep You could have factored or used the quadratic formula.

16. myininaya Group Title

It is more proper to say the x-intercepts are (3,0) and (-7,0) I would say it is informal to say they are 3 and -7

17. AriM Group Title

Yea, i understand.

18. myininaya Group Title

Coolness.