## anonymous one year ago Need help real quick, Its Quadratic Formula, I solved the question, but i wanna make sure my answer is right. The question is :

1. anonymous

The answer I got was |dw:1441264767920:dw|

2. anonymous

thank you! :) the answer on the worksheet says its |dw:1441265454395:dw| so could the worksheet be wrong?

3. skullpatrol

Ooops :( Let's try again..

4. anonymous

okayy, i understand it, but i just dont know how it got that when i have a different answer lol.

5. anonymous

so maybe i have to + and - it? idk

6. skullpatrol

Try using your calculator and sub the numbers back in.

7. anonymous

$3x^2-2x=9$$x^2-\frac{2}{3}x=3$ $c=\left(\frac{-\dfrac{2}{3}}{2}\right)=\left(-\frac{1}{3}\right)^2=\frac{1}{9}$ $x^2-\frac{2}{3}x\color{red}{+\frac{1}{9}} = 3 \color{red}{+\frac{1}{9}}$$\left(x-\frac{1}{3}\right)^2= \frac{28}{9}$$x-\frac{1}{3} = \pm \frac{\sqrt{28}}{3}$$\boxed{x=\pm \frac{\sqrt{28}}{3}+\frac{1}{3}}$

8. anonymous

You can check your answer by completing the square, if you're familiar with that method.

9. anonymous

And the answer can be simplified even further from what I have written btw.

10. anonymous

This is the method we are supposed to use : $x=-b \pm \sqrt{b^2-4ac}/2a$ over 2a

11. anonymous

would it be the same

12. wolf1728

The first part of that formula is already divided by 2a

13. anonymous

yeah

14. wolf1728

so what you typed would imply that you need to divide it by 2a again

15. anonymous

Okay so put your formula in quadratic form, $$ax^2+bx+c=0 \longrightarrow 3x^2-2x-9=0$$ identify your a, b and c and plug them in to the quadratic.

16. anonymous

ohh okay isee

17. skullpatrol

|dw:1441265969581:dw|

18. anonymous

yay our answers match @skullpatrol :)

19. anonymous

thanks! i see what i did wrong

20. skullpatrol

thanks for asking :-)