第1章 1.15

(1)

x3+6x2+9x=x(x2+6x+9)=x(x+3)2x^3 + 6x^2 + 9x = x(x^2 + 6x + 9) = x(x + 3)^2

(2)

a2+b2c22ab=(ab)2c2=(abc)(ab+c)a^2 + b^2 - c^2 - 2ab = (a - b)^2 - c^2 = (a - b - c)(a - b + c)

(3)

x3+x2x1=(x1)(x2+2x+1)=(x1)(x+1)2x^3 + x^2 - x - 1 = (x - 1)(x^2 + 2x + 1) = (x - 1)(x + 1)^2

(4)

a211ab+24b2=(a8b)(a3b)a^2 - 11ab + 24b^2 = (a - 8b)(a - 3b)

(5)

13x2+73x+4=13(x2+7x+12)=13(x+3)(x+4)\frac{1}{3}x^2 + \frac{7}{3}x + 4 = \frac{1}{3}(x^2 + 7x + 12) = \frac{1}{3}(x + 3)(x + 4)

(6)

6a219ab+10b2=(3a2b)(2a5b)6a^2 - 19ab + 10b^2 = (3a - 2b)(2a - 5b)

解説: r31bn1z