Question

Решите уравнение:
х^2-21=4х

Answer 1

${x}^{2} - 4x - 21 = 0 \ d = 16 + 4 times 21 = 100 = {10}^{2} \ x1 = frac{4 + 10}{2} = 7 \ х2 = frac{4 - 10}{2} = - 3$