Given \[ x^{2}+(k-1) x=-k+2 \] Show that the roots are real and rational for all
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Bonus Knowledge
To determine if the roots of the quadratic equation \[ x^{2}+(k-1)x + (k-2) = 0 \] are real and rational for all values of \( k \), we can examine the discriminant, \( D \), defined as \[ D = b^2 - 4ac \] where \( a = 1 \), \( b = k - 1 \), and \( c = k - 2 \). Substituting these values in, we get: \[ D = (k-1)^2 - 4 \cdot 1 \cdot (k - 2) \] Calculating the discriminant: \[ D = (k-1)^2 - 4(k - 2) = (k^2 - 2k + 1) - (4k - 8) = k^2 - 2k + 1 - 4k + 8 = k^2 - 6k + 9 \] This simplifies to \[ D = (k-3)^2 \] Since the square of any real number is always non-negative, \( D \geq 0 \). Thus, the roots are indeed real for all values of \( k \). Next, we need to check if the roots are rational. For the roots to be rational, the discriminant \( D \) must be a perfect square. Since \( D = (k-3)^2 \) is always a square (being the square of \( k-3 \)), the roots will be rational for all values of \( k \). In conclusion, the roots of the equation \( x^{2}+(k-1)x + (k-2) = 0 \) are real and rational for all \( k \).