SOLUTION: Dear sir/madam, Would you mind helping me to solve this equation and to get the value of r? 4r-2000r^-2=0 I calculated the following but know it is incorrect: 4r-2000r^-2

Algebra ->  Exponents-negative-and-fractional -> SOLUTION: Dear sir/madam, Would you mind helping me to solve this equation and to get the value of r? 4r-2000r^-2=0 I calculated the following but know it is incorrect: 4r-2000r^-2      Log On


   



Question 13802: Dear sir/madam,
Would you mind helping me to solve this equation and to get the value of r?
4r-2000r^-2=0
I calculated the following but know it is incorrect:
4r-2000r^-2=0
4r^-2(r^3-500)=0
Therefore,
4r^-2=0 or r^3-500=0
4/r^2=0 r^3=500
1/r^2=0 r=500^1/3
r^2=1/0 r=7.94
I can't continue on the left, because 1/0 is error. I only got one of the values of r is 7.94, but I could't get the other value of r.
Please reply soon and many thanks for your kind assistance.
On Ki


Answer by longjonsilver(2297) About Me  (Show Source):
You can put this solution on YOUR website!
4r-2000r%5E-2=0
4r+=+2000r%5E-2
4r+=+2000%2Fr%5E2
4r%5E3+=+2000
r%5E3+=+500
--> r+=+root%283%2C500%29
--> r+=+root%283%2C%28125%2A4%29%29
--> r+=+root%283%2C125%29root%283%2C4%29
--> r+=+5root%283%2C4%29%29

jon.