Asked by Chopsticks
X^1/3 - 2/5 = 0
x^1/3 = 2/3
x= 2/3^(1/3)
x=1.38
is that right?
Also
(x-4)^3/2 = -6
How do you do that?
x^1/3 = 2/3
x= 2/3^(1/3)
x=1.38
is that right?
Also
(x-4)^3/2 = -6
How do you do that?
Answers
Answered by
Reiny
x = 1.38 does not verify your first equation,
if I take the cuberoot of 1/38, I don't get 2/5
I see an error in your second line
x^(1/3) = 2/5
now cube both sides
x = 8/125
for your second, there is no "real" solution.
an exponent of 3/2 means, take the square root, then cube that result
since we cannot take the square root of -6, .......
if I take the cuberoot of 1/38, I don't get 2/5
I see an error in your second line
x^(1/3) = 2/5
now cube both sides
x = 8/125
for your second, there is no "real" solution.
an exponent of 3/2 means, take the square root, then cube that result
since we cannot take the square root of -6, .......
Answered by
Chopsticks
Reiny, after working it the first 1 over, i got .016
How would u work the second one? can you show me steps by step?
How would u work the second one? can you show me steps by step?
Answered by
Chris
If your first equation is x^(1/3) - 2/5 =0
then
x= (2/5)^3 = (2^3)/(5^3) = (8/125) = 0.064
for your second equation I believe you should do the following:
(x-4)^3/2 = -6
First raise both to the 2/3 power to get rid of the ^3/2.
(((x-4)^3/2)^(2/3)))=(-6)^(2/3)
=>(x-4)=((-6)^(2/3))=> x = ((-6)^(2/3))+4
=> x = 36^(1/3) + 4
then
x= (2/5)^3 = (2^3)/(5^3) = (8/125) = 0.064
for your second equation I believe you should do the following:
(x-4)^3/2 = -6
First raise both to the 2/3 power to get rid of the ^3/2.
(((x-4)^3/2)^(2/3)))=(-6)^(2/3)
=>(x-4)=((-6)^(2/3))=> x = ((-6)^(2/3))+4
=> x = 36^(1/3) + 4
Answered by
Reiny
did you not read my reply?
I worked out both of your questions
The answer you gave after my post still does not work
use to calculator to find the cuberoot of .016, you would get .25198 which is not equal to 2/5
but the answer I gave you, namely 8/125, has as its cuberoot 2/5
I worked out both of your questions
The answer you gave after my post still does not work
use to calculator to find the cuberoot of .016, you would get .25198 which is not equal to 2/5
but the answer I gave you, namely 8/125, has as its cuberoot 2/5
Answered by
Chopsticks
Ahh okay. I didn't get it at first, but now that I read it, I got it. Thanks alot!
Answered by
Reiny
Chris, for the second equation there is no solution
Did you verify your answer in the original equation??
that is..
is (7.3019)^1.5 = -6 ????
Did you verify your answer in the original equation??
that is..
is (7.3019)^1.5 = -6 ????
Answered by
Chris
I think they are two separate questions and since the -6 is on the right sideto find x one would square both sides and find the cube of that result then subtract add four. I could be mistaken.
Answered by
Chris
I think they are two separate questions and since the -6 is on the right sideto find x one would square both sides and find the cube root of that result then add four. I could be mistaken
Answered by
Damon
(x-4)^3/2 = -6
Chris, you can do what you said but it would be wrong.
what you said:
(x-4)^3 = 36
x-4 = 3.3
x = 7.3 HOWEVER
go back and check
3.3^3/2 = +6 NOT -6
In other words, when you squared both sides you threw the problem out with the bath water.
Chris, you can do what you said but it would be wrong.
what you said:
(x-4)^3 = 36
x-4 = 3.3
x = 7.3 HOWEVER
go back and check
3.3^3/2 = +6 NOT -6
In other words, when you squared both sides you threw the problem out with the bath water.
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