Is this question flawed?

StaryNight · #1 $Old$ November 21st, 2008, 01:23 PM

I am given the equation of a curve: y=x^3 - 5x - (2/x) where x is not equal to 0.

I am told that the points A and B which are (1,-2) and (-1,2) lie on it.

However, when one substitutes 1 and -1 into the equation one gets: -6 and 6 respectively.

I am pretty sure i am not going mad and this is a misprint (it is supposed to be a past exam question from what i gather.)

Am i right?

Thanks

galactus · #2 $Old$ November 21st, 2008, 01:47 PM

There is a typo in the equation.

If it were $x^{3}-5x+\frac{2}{x}$ , then it'll work OK.

CaptainBlack · #3 $Old$ November 21st, 2008, 01:48 PM

Quote:

Originally Posted by StaryNight $View Post$

I am given the equation of a curve: y=x^3 - 5x - (2/x) where x is not equal to 0.

I am told that the points A and B which are (1,-2) and (-1,2) lie on it.

However, when one substitutes 1 and -1 into the equation one gets: -6 and 6 respectively.

I am pretty sure i am not going mad and this is a misprint (it is supposed to be a past exam question from what i gather.)

Am i right?

Thanks

Prabably y=x^3 - 5x + (2/x) was intended.

CB