乗法公式(a+b)(a-b)同1

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== 乗法公式(a+b)(a-b) == ^【問題】
　次の式を展開しなさい．（正しい式をマウスで選びなさい．）
(1) (x+6)(x−6)解説

=

x2+12x+36 x2−12x+36 x2+6x+6

x2−6x+6 x2+36 x2−36

x2+12 x2−12

(2) (x+9)(x−9)解説

=

x2+18x+81 x2−18x+81 x2+9x+9

x2−9x+9 x2+81 x2−81

x2+18 x2−18

(3) (x+5)(x−5)解説

=

x2+10x+25 x2−10x+25 x2+5x+5

x2−5x+5 x2+25 x2−25

x2+10 x2−10

(4) (a+8b)(a−8b)解説

=

a2+16b2 a2−16b2 a2+16ab+64b2

a2−16ab+64b2 a2+64 a2−64

a2+64b2 a2−64b2

(5) $(a-\sqrt{2}b)(a + \sqrt{2}b)$ 解説

=

$a^2+ 2b^2$ $a^2-2b^2$ $a^2+ \sqrt{2}b^2$

$a^2-\sqrt{2}b^2$ $a^2+ 2$ $a^2-2$

$a^2+ 4b^2$ $a^2-4b^2$

(6) 103×97解説

=

9981 9983 9985 9987 9989

9991 9993 9995 9997 9999

10001 10003 10005 10007 10009

10011 10013 10015 10017 10019

(7) 10.5×9.5解説

=

99.05 99.15 99.25 99.35

99.45 99.55 99.65 99.75

99.85 99.95 100.05 100.15

100.25 100.35 100.45 100.55

100.65 100.75 100.85 100.95