Question

Решите уравнение: d^2+0.2*d+0.01-0.36*d^2=0

Answer 1

${d}^{2} + 0.2d + 0.01 - 0.36 {d}^{2} = 0 \\ 0.64 {d}^{2} + 0.2d + 0.01 = 0 \\ 64 {d}^{2} + 20d + 1 = 0 \\ dis = 400 - 64 \times 4 \times 1 = 144 \\ d1 = \frac{ - 20 + 12}{2 \times 64} = - \frac{ 1}{16} \\ d2 = \frac{ - 20 - 12}{2 \times 64} = - \frac{1}{4}$