第7章 7.10

(1)

x3=1x3+1=0(x+1)(x2x+1)=0x=1,1±142x=1,1±3i2x^3 = -1 \qquad x^3 + 1 = 0 \qquad (x+1)(x^2-x+1) = 0 \qquad x = -1, \frac{1 \pm \sqrt{1-4}}{2} \qquad x = -1, \frac{1 \pm \sqrt{3}i}{2}

(2)

x3=8x38=0(x2)(x2+2x+4)=0x=2,1±14x=2,1±3ix^3 = 8 \qquad x^3 - 8 = 0 \qquad (x-2)(x^2+2x+4) = 0 \qquad x = 2, -1 \pm \sqrt{1-4} \qquad x = 2, -1 \pm \sqrt{3}i

(3)

x41=0(x21)(x2+1)=0(x1)(x+1)(x2+1)=0x=±1,±ix^4 - 1 = 0 \qquad (x^2-1)(x^2+1) = 0 \qquad (x-1)(x+1)(x^2+1) = 0 \qquad x = \pm1, \pm i

解説: r31bn1z