quadratic equations

[tlg]

Hello could someone help me with this equation I get so far then Im stuck

72x-2 =2

 

[tlg]

[math]72x^-2=2[/math]

 

[Dr.Peterson]

Hello could someone help me with this equation I get so far then Im stuck

72x^-2 =2

[math]72x^{-2}=2[/math]

I've corrected both to what I think you mean.

This is not quadratic; and it may be important to see the original problem, in case you have made a mistake before this point.

But if it is correct, you might try multiplying both sides by x^2.

 

[pka]

Hello could someone help me with this equation I get so far then Im stuck
72x-2 =2

Or is it
[imath]72x-2=2\\72x=4\\x=\dfrac{4}{72}\\x=\dfrac{4}{8\cdot 9}\\x=\dfrac{1}{2\cdot 9}[/imath]

 

[Steven G]

Prof Peterson,
Are you sure about not calling that equation a quadratic equation since it can be written as one?
Steven

 

[tlg]

Oh thank you. I have not written it up quite right. It is 72 with negative x squared equals two.. sorry. I know th answer is x = 6 or x=-6 but I just need help with the steps. Thanks very much

 

[Dr.Peterson]

Oh thank you. I have not written it up quite right. It is 72 with negative x squared equals two.. sorry. I know th answer is x = 6 or x=-6 but I just need help with the steps. Thanks very much

That is the solution to the problem as I corrected it; but it is not read as "72 with negative x squared equals two", which would mean "72(-x)^2 = 2". Rather, it's "72 times x to the negative 2 power equals 2".

So please do as I suggested. (pka's suggestion is not your problem.)

Prof Peterson,
Are you sure about not calling that equation a quadratic equation since it can be written as one?
Steven

Yes, I am sure. Not everything that can be written as a quadratic equation is itself a quadratic equation. In particular, as negative exponents are not allowed in polynomials, this isn't even a polynomial equation. An equation is called quadratic when it can be written as ax^2 + bx + c = 0 using only addition, not multiplying by a power of x, or substituting 1/u for x, or anything like that. That is, it can be rearranged to that form.

 

[tlg]

Thank you

 

[Steven G]

That is the solution to the problem as I corrected it; but it is not read as "72 with negative x squared equals two", which would mean "72(-x)^2 = 2". Rather, it's "72 times x to the negative 2 power equals 2".

So please do as I suggested. (pka's suggestion is not your problem.)


Yes, I am sure. Not everything that can be written as a quadratic equation is itself a quadratic equation. In particular, as negative exponents are not allowed in polynomials, this isn't even a polynomial equation. An equation is called quadratic when it can be written as ax^2 + bx + c = 0 using only addition, not multiplying by a power of x, or substituting 1/u for x, or anything like that. That is, it can be rearranged to that form.

Thank you for your explanation. I now understand.