Which term describes the roots of the equation

2x^2 + 3x- 1 = 0?

(1) rational (3) equal

(2) irrational (4) imaginary

I guessed choice (2) and was right but I still do not know what makes the roots irrational in this case.

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- Jan 4th 2009, 01:51 PMmagentaritaRoots of Quadratic Equation
Which term describes the roots of the equation

2*x^*2 + 3*x*- 1 = 0?

(1) rational (3) equal

(2) irrational (4) imaginary

I guessed choice (2) and was right but I still do not know what makes the roots irrational in this case. - Jan 4th 2009, 02:05 PMnzmathman
The roots are found by the quadratic formula,

In your equation, , and .

So

This shows there are 2 real roots. Now 17 is a prime number - it can only be divided exactly by 1 and itself. The square root of any prime number is irrational - it cannot be expressed as a fraction. So the roots of the equation are therefore irrational. - Jan 5th 2009, 10:53 PMmagentaritanice....