## BrianWest 2 years ago help solving polinomial equations

1. BrianWest

\[x ^{3}+216=0\]

2. Mertsj

1. Subtract 216 from both sides 2. Take the third root of both sides.

3. BrianWest

what does it look like worked out, i am confused

4. inkyvoyd

Now now, don't you go human wolframing without giving the answer. ;)

5. Mertsj

Can you subtract 216 from both sides?

6. BrianWest

yes, i get x^3=-216

7. Mertsj

Do you know what a third root is?

8. Mertsj

For example, the third root of 8 is 2 because 2 raised to the third power is 8

9. BrianWest

yes, the thierd root of 216=6 x=6

10. Mertsj

|dw:1363827771232:dw|

11. Mertsj

What is the third root of -216?

12. BrianWest

-6i

13. BrianWest

-6 or 6i

14. Mertsj

Just plain -6 because -6 x -6 x -6 = -216

15. BrianWest

so my answer is -6... correct

16. Mertsj

Correct. Very good.

17. BrianWest

18. Mertsj

Find the p(a) be replacing each x with a Find 4p(a) by multiplying that result by 4

19. BrianWest

i have p(a) = 3a^2 -2a +5

20. BrianWest

my final answer is 4p(a) = 45 is this correct???

21. BrianWest

is this correct