## anonymous one year ago Solve x2 − 8x + 5 = 0 using the completing-the-square method.

1. anonymous

@hartnn Hi

2. hartnn

hello :) what have you tried?

3. anonymous

i got x and square root of 11

4. anonymous

I don't think i got it right

5. hartnn

ok, lets go step by step, x^2 -8x = -5 what did you add to both sides of this equation?

6. anonymous

16

7. hartnn

good! so left side became the perfect square of (x-4) $$(x-4)^2 = 16-5 \\ (x-4)^2=11$$ now take square root on both sides

8. anonymous

?

9. anonymous

11 can't be square rooted

10. anonymous

11. hartnn

right, keep it as $$\Large \sqrt{11}$$

12. anonymous

okay

13. hartnn

$$\sqrt{(x-4)^2} = x-4$$

14. anonymous

okay so x-4 = square root of 11

15. hartnn

$$\Large x-4 =\pm \sqrt {11}$$

16. hartnn

because there would be a negative root too

17. anonymous

okay but my answer choices are x = negative four plus or minus the square root of eleven x = four plus or minus the square root of eleven x = negative four plus or minus the square root of five x = four plus or minus the square root of five

18. anonymous

That isn't "x ="

19. hartnn

20. anonymous

OHHHH

21. hartnn

$$\Large x = 4\pm \sqrt{11}$$

22. anonymous

OMG I LOVE YOU <3333333333333333333333333333333333

23. anonymous

No hetero

24. hartnn

me too :) welcome ^_^