b: \(\left|x_1-x_2\right|=\sqrt{\left(x_1-x_2\right)^2}\)
\(=\sqrt{\left(x_1+x_2\right)^2-4x_1x_2}\)
\(=\sqrt{\left(\dfrac{3}{2}\right)^2-4\cdot\dfrac{-7}{2}}=\dfrac{\sqrt{65}}{2}\)
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