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(9)$(2x-3)^{2}=$
$4x^{2}-12x+9$
.答案
(9)$4x^{2}-12x+9$
(10)若$x^{2}-6x+k^{2}$是一个完全平方式,则$k=$
$\pm 3$
.答案
(10)$\pm 3$
(11)一种细菌的直径为0.000 001 5 m.用科学记数法表示该直径为
$1.5× 10^{-6}$
m.答案
(11)$1.5× 10^{-6}$
3. 计算.
(1)$(-2a^{2}b^{3})(-3a)^{2};$
(2)$3x(9x^{2}-3ax+a^{2});$
(3)$(3x+2y)(x-y);$
(4)$(3x-2y)(-2y-3x);$
(5)$(-4a-1)^{2};$
(6)$(a-\frac{1}{2})(a^{2}-\frac{1}{4})(a+\frac{1}{2});$
(7)$(a+b-c)(b-a+c);$
(8)$1998^{2}-1999× 1997;$
(9)$999^{2}-1002× 998.$
(1)$(-2a^{2}b^{3})(-3a)^{2};$
(2)$3x(9x^{2}-3ax+a^{2});$
(3)$(3x+2y)(x-y);$
(4)$(3x-2y)(-2y-3x);$
(5)$(-4a-1)^{2};$
(6)$(a-\frac{1}{2})(a^{2}-\frac{1}{4})(a+\frac{1}{2});$
(7)$(a+b-c)(b-a+c);$
(8)$1998^{2}-1999× 1997;$
(9)$999^{2}-1002× 998.$
答案
(1)$-18a^{4}b^{3}$
(2)$27x^{3}-9ax^{2}+3a^{2}x$
(3)$3x^{2}-xy-2y^{2}$
(4)$4y^{2}-9x^{2}$
(5)$16a^{2}+8a+1$
(6)$a^{4}-\frac{1}{2}a^{2}+\frac{1}{16}$
(7)$b^{2}-a^{2}-c^{2}+2ac$
(8)1
(9)$-1\ 995$
(2)$27x^{3}-9ax^{2}+3a^{2}x$
(3)$3x^{2}-xy-2y^{2}$
(4)$4y^{2}-9x^{2}$
(5)$16a^{2}+8a+1$
(6)$a^{4}-\frac{1}{2}a^{2}+\frac{1}{16}$
(7)$b^{2}-a^{2}-c^{2}+2ac$
(8)1
(9)$-1\ 995$
