|x^2-5x-1|=7

解

x^{2} - 5 x - 1 = 7

x = \frac{5 - 57}{2} or x = 2 or x = 3 or x = \frac{5 + 57}{2}

十進法表記

x = - 1.27491 \dots, x = 2, x = 3, x = 6.27491 \dots

解答ステップ

x^{2} - 5 x - 1 = 7

絶対規則を適用する:

∣ u ∣ = a, a > 0

の場合は

u = a

u = - a

x^{2} - 5 x - 1 = - 7 or x^{2} - 5 x - 1 = 7

x^{2} - 5 x - 1 = - 7 or x^{2} - 5 x - 1 = 7

(x = 2 or x = 3) or (x = \frac{5 - 57}{2} or x = \frac{5 + 57}{2})

x = \frac{5 - 57}{2} or x = 2 or x = 3 or x = \frac{5 + 57}{2}