Question

Last two.

Answer 1

Find the real solutions of the equation.

4x^2/3 -31x ^1/3 -8=0

Answer 2

@dinamix @freckles @Vocaloid

Answer 3

w= -1/4
w= 8

Answer 4

hm, we can do another substitution to make the algebra a bit simpler

let's let a = x^(1/3)

that gives us

4a^2 - 31a - 8 which factors to

(4a+1)(a-8) = 0

know where to go from here?

Answer 5

Yeah..

w= -1/4
w= 8

Answer 6

Then I got

x= -1/16 and x= 512

Answer 7

But my answers are wrong so I messed up somewhere

Answer 8

x^ 2/3 = -1/4

x^1/3 =8

Answer 9

8*8*8= 512

x=512

Answer 10

x^1/3 = -1/4 and x^1/3 = 8 thats only

Answer 11

u have too find x

Answer 12

Yes I know that

Answer 13

The one x= 512

Answer 14

x= -1/4 ^3/2

Answer 15

4*4= 16

So is the answer -1/16 or -1/8 ???

Answer 16

As dinamix is saying, you should have `x^1/3 = -1/4` and NOT `x^2/3 = -1/4`


You let w = x^1/3, so if w = -1/4, then `x^1/3 = -1/4`


solve x^1/3 = -1/4 for x

Answer 17

x= -1/ 64

Answer 18

I figured that was a miss type... Why is 2/3 now 1/3???

Answer 19

you made w = x^1/3

that allowed you to go from `4x^2/3 -31x ^1/3 -8=0` to `4w^2 - 31w - 8 = 0`

Answer 20

solving 4w^2 - 31w - 8 = 0 gives w = -1/4 or w = 8

Answer 21

cuz suppose a= x^1/3 not 2/3

Answer 22

if w = x^1/3, then w^2 = x^2/3

Answer 23

Yes w= x^1/3
But w^2= x^2/3

Answer 24

x=512 and x= -1/64

Answer 25

the solutions w = -1/4 or w = 8 are for w and not for w^2

Answer 26

Yes thats what ive been saying

Answer 27

I have w solved already as 512.. Im now trying to solve w^2...

How did you get 64 @dinamix

Answer 28

I thought I only times it 2 times not 3

Answer 29

dinamix cubed both sides of x^1/3 = -1/4

Answer 30

yup this so we find x=-1/64

Answer 31

I see okay

Answer 32

Last problem

Answer 33

so sec u sould understand okey ?

Answer 34

I got this one wrong and Id like it checked before redoing number 13.

(x-3)^2/3 =25

Answer 35

Yes I understand. Thank you

Answer 36

a = (x-3)^1/3

Answer 37

and will be a^2=25

Answer 38

My final answer was x= 128

Answer 39

But its wrong

Answer 40

a=5 or a=-5

Answer 41

Whered you get the negative 5 from?? O.o

Answer 42

hmm (-5)^2 = 25 right

Answer 43

?

Answer 44

Yes

Answer 45

so u understand

Answer 46

now

Answer 47

I get where -122 comes from.. But where did the -5 come from?

Answer 48

x=128 and x=-122

Answer 49

\[\frac{ 0\pm \sqrt{4*25} }{ 2 }\]

Answer 50

a^2-25 = 0 u have to solve it u get 5 and -5

Answer 51

@Destinyyyy

Answer 52

Ohhh.. I didnt do that. I just added 3 to 125 and thought I was done. So I have to put it into the qe okay

Answer 53

Okay.. Im starting the redo question

Answer 54

ok i am going to sleep , i hope u understand

Answer 55

I believe I do..

Answer 56

New problem..

(x-5) ^2/3 =4

Answer 57

-3,13

Answer 58

oops @Destinyyyy I forgot to consider other real solution for that previous problem.

Answer 59

Its okay. I wrote a number wrong in the original problem

Answer 60

Finally im done and can take the quiz

Answer 61

good job

Answer 62

Thank you.. Do you mind checking my answers for the quiz in a new question?

Answer 63

ok sure