|x^2-4x-5|=4

解

x^{2} - 4 x - 5 = 4

x = 2 - 13 or x = 2 - 5 or x = 2 + 5 or x = 2 + 13

十進法表記

x = - 1.60555 \dots, x = - 0.23606 \dots, x = 4.23606 \dots, x = 5.60555 \dots

解答ステップ

x^{2} - 4 x - 5 = 4

絶対規則を適用する:

∣ u ∣ = a, a > 0

の場合は

u = a

u = - a

x^{2} - 4 x - 5 = - 4 or x^{2} - 4 x - 5 = 4

x^{2} - 4 x - 5 = - 4 or x^{2} - 4 x - 5 = 4

(x = 2 - 5 or x = 2 + 5) or (x = 2 - 13 or x = 2 + 13)

x = 2 - 13 or x = 2 - 5 or x = 2 + 5 or x = 2 + 13