해법
확장 (2x+4x1)20
해법
1048576x20+2621440x18+3112960x16+2334720x14+1240320x12+496128x10+155040x8+38760x6+862985x4+1620995x2+25646189+1024x220995+32768x462985+32768x64845+524288x84845+2097152x10969+268435456x124845+536870912x14285+233x1695+235x185+420x201
솔루션 단계
(2x+4x1)20
이항 정리 적용: (a+b)n=i=0∑n(in)a(n−i)bia=2x,b=4x1
=i=0∑20(i20)(2x)(20−i)(4x1)i
합계 확장
=0!(20−0)!20!(2x)20(4x1)0+1!(20−1)!20!(2x)19(4x1)1+2!(20−2)!20!(2x)18(4x1)2+3!(20−3)!20!(2x)17(4x1)3+4!(20−4)!20!(2x)16(4x1)4+5!(20−5)!20!(2x)15(4x1)5+6!(20−6)!20!(2x)14(4x1)6+7!(20−7)!20!(2x)13(4x1)7+8!(20−8)!20!(2x)12(4x1)8+9!(20−9)!20!(2x)11(4x1)9+10!(20−10)!20!(2x)10(4x1)10+11!(20−11)!20!(2x)9(4x1)11+12!(20−12)!20!(2x)8(4x1)12+13!(20−13)!20!(2x)7(4x1)13+14!(20−14)!20!(2x)6(4x1)14+15!(20−15)!20!(2x)5(4x1)15+16!(20−16)!20!(2x)4(4x1)16+17!(20−17)!20!(2x)3(4x1)17+18!(20−18)!20!(2x)2(4x1)18+19!(20−19)!20!(2x)1(4x1)19+20!(20−20)!20!(2x)0(4x1)20
0!(20−0)!20!(2x)20(4x1)0간소화하다 :1048576x20
1!(20−1)!20!(2x)19(4x1)1간소화하다 :2621440x18
2!(20−2)!20!(2x)18(4x1)2간소화하다 :3112960x16
3!(20−3)!20!(2x)17(4x1)3간소화하다 :2334720x14
4!(20−4)!20!(2x)16(4x1)4간소화하다 :1240320x12
5!(20−5)!20!(2x)15(4x1)5간소화하다 :496128x10
6!(20−6)!20!(2x)14(4x1)6간소화하다 :155040x8
7!(20−7)!20!(2x)13(4x1)7간소화하다 :38760x6
8!(20−8)!20!(2x)12(4x1)8간소화하다 :862985x4
9!(20−9)!20!(2x)11(4x1)9간소화하다 :1620995x2
10!(20−10)!20!(2x)10(4x1)10간소화하다 :25646189
11!(20−11)!20!(2x)9(4x1)11간소화하다 :1024x220995
12!(20−12)!20!(2x)8(4x1)12간소화하다 :32768x462985
13!(20−13)!20!(2x)7(4x1)13간소화하다 :32768x64845
14!(20−14)!20!(2x)6(4x1)14간소화하다 :524288x84845
15!(20−15)!20!(2x)5(4x1)15간소화하다 :2097152x10969
16!(20−16)!20!(2x)4(4x1)16간소화하다 :268435456x124845
17!(20−17)!20!(2x)3(4x1)17간소화하다 :536870912x14285
18!(20−18)!20!(2x)2(4x1)18간소화하다 :233x1695
19!(20−19)!20!(2x)1(4x1)19간소화하다 :235x185
20!(20−20)!20!(2x)0(4x1)20간소화하다 :420x201
=1048576x20+2621440x18+3112960x16+2334720x14+1240320x12+496128x10+155040x8+38760x6+862985x4+1620995x2+25646189+1024x220995+32768x462985+32768x64845+524288x84845+2097152x10969+268435456x124845+536870912x14285+233x1695+235x185+420x201