第1章 1.6

(1)

$(x+2)^2 = x^2+4x+4$

(2)

$(a-4)^2 = a^2-8a+16$

(3)

$(2a+5b)^2 = 4a^2+20ab+25b^2$

(4)

$(a+7b)(a-7b) = a^2-49b^2$

(5)

$(2x-3y)(2x+3y) = 4x^2-9y^2$

(6)

$(x-5)(x+6) = x^2+x-30$

(7)

$(x-2y)(x+3y) = x^2+xy-6y^2$

(8)

$(3x-1)(2x-5) = 6x^2-17x+5$

(9)

$(2x+3)(5x-4) = 10x^2+7x-12$

(10)

$\left(a-\frac{1}{2}\right)\left(a-\frac{1}{3}\right) = a^2-\frac{5}{6}a+\frac{1}{6}$