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## kirk.freedman 3 years ago Use the quadratic formula to solve the equation. x^2 – 7x – 6 = 0 Show work please.

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1. winterfez

x^2-7x-6=0?

2. lilg132

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

3. kirk.freedman

yes it is an exponent

4. lilg132

x2 = a -7x = b -6 = c x2 = 1 -7x = -7 -6 = -6

5. tcarroll010

$x = \frac{ -b \pm \sqrt{b ^{2}-4ac} }{ 2a }$where a=1, b=-7, and c =-6 This is because your equation is in the standard form of ax^2 + bx + c = 0. So, now, just make the substitutions.

6. kirk.freedman

Hmm, ok thanks, let me work this out and I will reply to what I got to check if it is right.

7. tcarroll010

Hint: after you make your substitutions, pay special attention to the expression within the radical (the square root sign). You will see that the numbet in the radical is positive, so you will have two real solutions. But your final solution will have a radical in it.

8. winterfez

|dw:1354234621716:dw|

9. tcarroll010

Are you able to identify the variables a, b, and c and make the substitutions?

10. kirk.freedman

Yes, I got to the step that winterfezz last showed, but I don't know what to do now

11. tcarroll010

Start with the expression within the radical. Start with (-7)^2. That is the same as 7^2.

12. winterfez

|dw:1354234898685:dw| you get 2 answers

13. tcarroll010

And when you have a negative number times a positive number, the product will be negative.

14. tcarroll010

So, can you determine (-7)^2 ?

15. tcarroll010

(-7)^2 is the same as (-7)(-7) and that is the same as (7)(7)

16. kirk.freedman

Yes, tcarroll, I know all that basic math stuff xD I am at the part where I have |dw:1354235055422:dw|

17. tcarroll010

That's good!. Because that is your final answer! Well done!

18. kirk.freedman

So I do not simplify it further?

19. tcarroll010

That's as far as you can take it.

20. tcarroll010

It is customary to leave it with the +- sign

21. kirk.freedman

Ok, so no decimal needed, I just leave it as this?

22. tcarroll010

That's good just like that.

23. kirk.freedman

Thank both of you very much!:)

24. tcarroll010

$\frac{ 7\pm \sqrt{73} }{ 2 }$Like that

25. tcarroll010

You're very welcome!

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