given that \( 4(y-2)^{2}=k(y-1) \), where k is a constant. (i) Show hat the sum of the roots equals their product. (ii) Find the value for which the difference between the roots is \( 33 / 4 \)
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Let's start solving \( 4(y-2)^{2} = k(y-1) \). Expanding the left side, we have: \[ 4(y-2)^{2} = 4(y^2 - 4y + 4) = 4y^2 - 16y + 16. \] Now, rearranging the equation gives us: \[ 4y^2 - 16y + 16 - k(y - 1) = 0. \] Expanding the term involving \( k \): \[ 4y^2 - 16y + 16 - ky + k = 0. \] Now, combine the terms: \[ 4y^2 - (16 + k)y + (16 + k) = 0. \] Let's denote \( a = 4 \), \( b = -(16 + k) \), and \( c = (16 + k) \). For a quadratic equation \( ay^2 + by + c = 0 \), the sum of the roots \( r_1 + r_2 = -\frac{b}{a} \) and the product of the roots \( r_1 r_2 = \frac{c}{a} \). Calculating the sum of the roots: \[ r_1 + r_2 = -\frac{-(16 + k)}{4} = \frac{16 + k}{4}. \] Calculating the product of the roots: \[ r_1 r_2 = \frac{(16 + k)}{4}. \] For the statement "the sum of the roots equals their product," we have: \[ \frac{16 + k}{4} = \frac{(16 + k)}{4}. \] This shows that indeed \( r_1 + r_2 = r_1 r_2 \). Now, to find the value of \( k \) for which the difference between the roots \( |r_1 - r_2| = \frac{33}{4} \): Using the formula for the difference of roots: \[ |r_1 - r_2| = \sqrt{(r_1 + r_2)^2 - 4r_1 r_2} = \sqrt{\left(\frac{16 + k}{4}\right)^2 - 4 \cdot \frac{(16 + k)}{4}}. \] Let’s simplify this: \[ |r_1 - r_2| = \sqrt{\frac{(16 + k)^{2}}{16} - (16 + k)} = \sqrt{\frac{(16 + k)^{2} - 16(16 + k)}{16}} = \sqrt{\frac{(16 + k)(16 + k - 16)}{16}} = \sqrt{\frac{(k)(k)}{16}} = \frac{k}{4}. \] For this to equal \( \frac{33}{4} \): \[ \frac{k}{4} = \frac{33}{4} \implies k = 33. \] Thus, the final values are: (i) The sum of the roots equals their product, and (ii) The value of \( k \) for which the difference between the roots is \( \frac{33}{4} \) is \( k = 33 \).