## anonymous one year ago Solve x2 − 3x = −8

1. anonymous

@Michele_Laino

2. pooja195

a ,b , c values are $\huge\rm Ax^2+Bx+C=0$ where a =leading coefficient b= leading coefficient c= constant term So we need to add 8 to both sides $\huge~\rm~ x^2 − 3x+8$ Now factor from here What numbers multiply to make 8 but add to make -3? if there are none the answer would be prime

3. anonymous

@ganeshie8 @Hero

4. pooja195

?

5. anonymous

idk what numbers multiply to 8 and add to -3

6. anonymous

@pooja195

7. pooja195

Then clearly there is not solution :) reread what i wrote are you given options?

8. anonymous

no solution isnt an option

9. pooja195

What are the options?

10. anonymous

Um I don't know how to right them out

11. pooja195

Just type them out

12. pooja195

Or scrnshot

13. anonymous

okay hold on

14. anonymous

15. pooja195

I havent learned "i" yet.... @UsukiDoll

16. anonymous

17. UsukiDoll

HUH?! O_O! that was random

18. UsukiDoll

yeah use quadratics on this equation... use discriminant formula b^2-4ac to see if we have a perfect square or not perfect square - we can factor not a perfect square - use quadratic formula

19. anonymous

wait what do i do?

20. UsukiDoll

$\huge~\rm~ x^2 − 3x+8$ where a = 1, b = -3, and c = 8 plug it into the discriminant formula which is b^2-4ac $\LARGE (-3)^2-4(1)(8)$

21. anonymous

okay what next?

22. UsukiDoll

$\LARGE (-3)^2-4(1)(8)$ $\LARGE 9-32 = -23$ not a perfect square and a negative... ok looks like we're going to have complex roots.

23. UsukiDoll

now we solved the b^2-4ac already so that makes the quadratic formula a bit easier $\LARGE \frac{ -b \pm \sqrt{b^2-4ac}}{2a}$

24. UsukiDoll

since a = 1, b = -3, and c = 8 $\LARGE \frac{ -(-3) \pm \sqrt{-23}}{2}$ negatives aren't allowed in the radical...so we write an i which stands for imaginary. $\LARGE \frac{ 3 \pm \sqrt{23}i}{2}$

25. anonymous

so the answer would be b?

26. UsukiDoll

wait... I haven't looked at that portion yet.

27. UsukiDoll

.docx hates me :(

28. anonymous

okay ill try to get it on something else

29. UsukiDoll

finally got through to it.. it is the second choice.

30. anonymous

Thank you!!!!