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乘法公式. 國中數學 第 3 冊. ( a + b )( c + d ) = ac + bc + ad + bd. a + b. a. b. ac. ( a + b ) × c. bc. c. c + d. ad. bd. ( a + b ) × d. d. ( a + b ) × ( c + d ). = ( a + b ) × c + ( a + b ) × d. = ac + bc + ad + bd. 4 1 × 5 3. 1 2 3. 2 0 5. 2 1 7 3. - PowerPoint PPT Presentation
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乘法公式
國中數學第 3 冊
交通大網路學習專班
c + d
( a + b )( c + d )= ac + bc + ad + bd
ac bc
ad bd
a + b
( a + b ) × c
( a + b ) × d
( a + b ) × ( c + d )
= ( a + b ) × c + ( a + b ) × d
= ac + bc + ad + bd
a b
c
d
交通大網路學習專班
( a + b )( c + d )= ac + bc + ad + bd
41 ×53
= ( 40 + 1 ) × ( 50 + 3 )
= 40 × 50 + 1 × 50 + 40 × 3 + 1 × 3
= 2000 + 50 + 120 + 3
= 2173
41 × 3
41 × 50
4 1× 5 3
1 2 3
2 0 5
2 1 7 3
交通大網路學習專班
( a + b )( c + d )= ac + bc + ad + bd
a = x , b = 2 , c = x , d = 3
( x + 2 )( x + 3 )x
3
x 2
x + 2
x + 3
x2 2 x
63 x
= x2 + 2x + 3x + 6
= x2 + 5x +6
交通大網路學習專班
( a + b ) 2 = a2 + 2ab + b2
a2
b2
ab
ab
a
a
b
b
a + b
a + b
( a + b ) 2
=( a + b ) × ( a + b )
= a2 + ab +ab + b2
= a2 + 2ab + b2
交通大網路學習專班
( a + b ) 2 = a2 + 2ab + b2
10.6 2
=( 10 + 0.6 ) 2 = 102 + 2 × 10 × 0.6 + 0.62
= 100 + 12 + 0.36
= 112.36
( a + b ) 2 = a2 + 2 × a × b + b2 hint
交通大網路學習專班
( a – b ) 2 = a2 – ab + b2 – ab( a – b ) 2 = a2 – ab + b2 – ab
( a – b ) 2
a
b
aa
b
a b
a – b
a – b
a2
b2
a b
= a2 – 2ab + b2
交通大網路學習專班
( a – b ) 2 = a2 – 2ab + b2
9.92 = ( 10 – 0.1 ) 2
= 102 – 2 × 10 × 0.1 + ( 0.1 ) 2
= 100 – 2 + 0.01
= 98.01
982 = ( 100 – 2 ) 2
= 1002 – 2 × 100 × 2 + 4
= 10000 – 400 + 4
= 9604
a2 – 2 × a × b + b2
hint
a2 – 2 × a × b + b2
hint
交通大網路學習專班
b2
( a + b )( a – b ) = a2 – b2
a
b
aa
a + b
a – b
bb
交通大網路學習專班
( a + b )( a – b ) = a2 – b2
2502 × 2498
= ( 2500 + 2 ) × ( 2500 – 2 )
= 25002 – 22
= 6250000 – 4
= 6249996
100.3 × 99.7
= ( 100 + 0.3 ) × ( 100 – 0.3 )
= 1002 – 0.32
= 10000 – 0.09
= 9999.91