해법
확장 n45(n+2x−2)4
해법
n480x4+n3160x3−n4320x3+n2120x2−n3480x2+n4480x2+n40x−n2240x+n3480x−n4320x+5−n40+n2120−n3160+n480
솔루션 단계
n45(n+2x−2)4
(n+2x−2)4=16x4+32nx3−64x3+24n2x2−96nx2+96x2+8n3x−48n2x+96nx−64x+n4−8n3+24n2−32n+16
=n45(16x4+32nx3−64x3+24n2x2+96x2−96nx2+8n3x+96nx−48n2x−64x+n4+24n2+16−8n3−32n)
5(16x4+32nx3−64x3+24n2x2−96nx2+96x2+8n3x−48n2x+96nx−64x+n4−8n3+24n2−32n+16)확대한다:80x4+160nx3−320x3+120n2x2−480nx2+480x2+40n3x−240n2x+480nx−320x+5n4−40n3+120n2−160n+80
=n480x4+160nx3−320x3+120n2x2−480nx2+480x2+40n3x−240n2x+480nx−320x+5n4−40n3+120n2−160n+80
분수 규칙 적용: ca±b=ca±cbn480x4+160nx3−320x3+120n2x2−480nx2+480x2+40n3x−240n2x+480nx−320x+5n4−40n3+120n2−160n+80=n480x4+n4160nx3−n4320x3+n4120n2x2−n4480nx2+n4480x2+n440n3x−n4240n2x+n4480nx−n4320x+n45n4−n440n3+n4120n2−n4160n+n480=n480x4+n4160nx3−n4320x3+n4120n2x2−n4480nx2+n4480x2+n440n3x−n4240n2x+n4480nx−n4320x+n45n4−n440n3+n4120n2−n4160n+n480
n4160nx3=n3160x3
n4120n2x2=n2120x2
n4480nx2=n3480x2
n440n3x=n40x
n4240n2x=n2240x
n4480nx=n3480x
n45n4=5
n440n3=n40
n4120n2=n2120
n4160n=n3160
=n480x4+n3160x3−n4320x3+n2120x2−n3480x2+n4480x2+n40x−n2240x+n3480x−n4320x+5−n40+n2120−n3160+n480