Friend just called me up with a math question...can't figure it out

[MangoTBG]

x^(1/4)-10x^(1/8)+21=0

Solve for x.

He gave me this as well:

My instructor mentioned something along the lines of this: t=x^(1/8) in this equation: at^2+bt+c=0

It's been 3 years since I've taken any math course, the last of which was Calc 2 I thought I would be of more help to him...maybe you guys can help me save the day!

THanks

 

[DAGTA]

Raise everything to the 8th power and then take a look at your equation and the equation the instructor mentioned.

 

[PurdueRy]

Substitute in:

t^2-10t+21 = 0

solve

(t-7)(t-3) = 21

t = 7,3

t = x^(1/8)
x = 7^8 or 3^8

 

[MangoTBG]

Originally posted by: PurdueRy
Substitute in:

t^2-10t+21 = 0

solve

(t-7)(t-3) = 21

t = 7,3

t = x^(1/8)
x = 7^8 or 3^8

Thank you

 

[Syringer]

= (x^1/8 - 7) * (x^1/8 - 3)

 

[So]

Originally posted by: PurdueRy
Substitute in:

t^2-10t+21 = 0

solve

(t-7)(t-3) = 21

t = 7,3

t = x^(1/8)
x = 7^8 or 3^8

/thread

 

[chuckywang]

Originally posted by: DAGTA
Raise everything to the 8th power and then take a look at your equation and the equation the instructor mentioned.

You're crazy.

Factor the equation as:

(x^(1/8) -3)*(x^(1/8)-7) = 0

which means x^(1/8) = 3 or 7, so x=3^8 or 7^8.

 

[Toastedlightly]

Originally posted by: chuckywang

Originally posted by: DAGTA
Raise everything to the 8th power and then take a look at your equation and the equation the instructor mentioned.

You're crazy.

Factor the equation as:

(x^(1/8) -3)*(x^(1/8)-7) = 0

which means x^(1/8) = 3 or 7, so x=3^8 or 7^8.

factoring by hand for the win!

 

[BrokenVisage]

Now that were done with the easy stuff... try and figure this one out:

5 + 5 + 5 = 550

Write that equation down on a peice of paper and draw a straight line ANYWHERE to make it true. (and no, you can't put it through the equal sign, you need the equation to be solved)

 

[PurdueRy]

Originally posted by: BrokenVisage
Now that were done with the easy stuff... try and figure this one out:

5 + 5 + 5 = 550

Write that equation down on a peice of paper and draw a straight line ANYWHERE to make it true. (and no, you can't put it through the equal sign, you need the equation to be solved)

add a line to the plus sign turning it into a 4

 

[DAGTA]

Originally posted by: chuckywang

Originally posted by: DAGTA
Raise everything to the 8th power and then take a look at your equation and the equation the instructor mentioned.

You're crazy.

Factor the equation as:

(x^(1/8) -3)*(x^(1/8)-7) = 0

which means x^(1/8) = 3 or 7, so x=3^8 or 7^8.

When someone asks for help with their homework online, I don't like to make it too easy for them. I also don't just give out the answers.

 

[chuckywang]

Originally posted by: DAGTA

Originally posted by: chuckywang

Originally posted by: DAGTA
Raise everything to the 8th power and then take a look at your equation and the equation the instructor mentioned.

You're crazy.

Factor the equation as:

(x^(1/8) -3)*(x^(1/8)-7) = 0

which means x^(1/8) = 3 or 7, so x=3^8 or 7^8.

When someone asks for help with their homework online, I don't like to make it too easy for them. I also don't just give out the answers.

At least guide them towards the right way to do the problem, not the wrong way.

 

[Schfifty Five]

Originally posted by: PurdueRy

Originally posted by: BrokenVisage
Now that were done with the easy stuff... try and figure this one out:

5 + 5 + 5 = 550

Write that equation down on a peice of paper and draw a straight line ANYWHERE to make it true. (and no, you can't put it through the equal sign, you need the equation to be solved)

add a line to the plus sign turning it into a 4

You so smart.

 

[DAGTA]

Originally posted by: chuckywang

Originally posted by: DAGTA

Originally posted by: chuckywang

Originally posted by: DAGTA
Raise everything to the 8th power and then take a look at your equation and the equation the instructor mentioned.

You're crazy.

Factor the equation as:

(x^(1/8) -3)*(x^(1/8)-7) = 0

which means x^(1/8) = 3 or 7, so x=3^8 or 7^8.

When someone asks for help with their homework online, I don't like to make it too easy for them. I also don't just give out the answers.

At least guide them towards the right way to do the problem, not the wrong way.

My suggestion was to help the OP see how the original equation relates to the example given by the professor.

Edit: re-worded to clarify