2х^2 - 5x+c=0;x1-x2 =1.5. Найдите С

$2x^2 - 5x + c = 0 \\ D = 25 - 2 \cdot 4 \cdot c = 25 - 8c \\ x_1 = \frac{5 + \sqrt{25 - 8c} }{4} \\ \\ x_2 = \frac{5 - \sqrt{25 - 8c} }{4} \\ \\ x_1 - x_2 = \frac{5 + \sqrt{25 - 8c} }{4} - \frac{5 - \sqrt{25 - 8c} }{4} = \frac{ \sqrt{25 - 8c} }{2} \\ \\ \frac{ \sqrt{25 - 8c} }{2} = 1,5 \\ \sqrt{25 - 8c} = 3 \\ 25 - 8c = 9 \\ 16 - 8c = 0 \\ c = 2$
Ответ: c = 2.