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

1. anonymous

x^2-7x-6=0?

2. lilg132

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

3. anonymous

yes it is an exponent

4. lilg132

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

5. anonymous

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

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

7. anonymous

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. anonymous

|dw:1354234621716:dw|

9. anonymous

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

10. anonymous

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

11. anonymous

12. anonymous

13. anonymous

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

14. anonymous

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

15. anonymous

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

16. anonymous

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

17. anonymous

18. anonymous

So I do not simplify it further?

19. anonymous

That's as far as you can take it.

20. anonymous

It is customary to leave it with the +- sign

21. anonymous

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

22. anonymous

That's good just like that.

23. anonymous

Thank both of you very much!:)

24. anonymous

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

25. anonymous

You're very welcome!