해법
8sin3(x)−6sin(x)+1=0
해법
x=0.17453…+2πn,x=π−0.17453…+2πn,x=0.87266…+2πn,x=π−0.87266…+2πn,x=−1.22173…+2πn,x=π+1.22173…+2πn
+1
도
x=10∘+360∘n,x=170∘+360∘n,x=50∘+360∘n,x=130∘+360∘n,x=−70∘+360∘n,x=250∘+360∘n솔루션 단계
8sin3(x)−6sin(x)+1=0
대체로 해결
8sin3(x)−6sin(x)+1=0
하게: sin(x)=u8u3−6u+1=0
8u3−6u+1=0:u≈0.17364…,u≈0.76604…,u≈−0.93969…
8u3−6u+1=0
다음을 위한 하나의 솔루션 찾기 8u3−6u+1=0 뉴턴-랩슨을 이용하여:u≈0.17364…
8u3−6u+1=0
뉴턴-랩슨 근사 정의
f(u)=8u3−6u+1
f′(u)찾다 :24u2−6
dud(8u3−6u+1)
합계/차이 규칙 적용: (f±g)′=f′±g′=dud(8u3)−dud(6u)+dud(1)
dud(8u3)=24u2
dud(8u3)
정수를 빼라: (a⋅f)′=a⋅f′=8dud(u3)
전원 규칙을 적용합니다: dxd(xa)=a⋅xa−1=8⋅3u3−1
단순화=24u2
dud(6u)=6
dud(6u)
정수를 빼라: (a⋅f)′=a⋅f′=6dudu
공통 도함수 적용: dudu=1=6⋅1
단순화=6
dud(1)=0
dud(1)
상수의 도함수: dxd(a)=0=0
=24u2−6+0
단순화=24u2−6
렛 u0=0계산하다 un+1 까지 Δun+1<0.000001
u1=0.16666…:Δu1=0.16666…
f(u0)=8⋅03−6⋅0+1=1f′(u0)=24⋅02−6=−6u1=0.16666…
Δu1=∣0.16666…−0∣=0.16666…Δu1=0.16666…
u2=0.17361…:Δu2=0.00694…
f(u1)=8⋅0.16666…3−6⋅0.16666…+1=0.03703…f′(u1)=24⋅0.16666…2−6=−5.33333…u2=0.17361…
Δu2=∣0.17361…−0.16666…∣=0.00694…Δu2=0.00694…
u3=0.17364…:Δu3=0.00003…
f(u2)=8⋅0.17361…3−6⋅0.17361…+1=0.00019…f′(u2)=24⋅0.17361…2−6=−5.27662…u3=0.17364…
Δu3=∣0.17364…−0.17361…∣=0.00003…Δu3=0.00003…
u4=0.17364…:Δu4=1.085E−9
f(u3)=8⋅0.17364…3−6⋅0.17364…+1=5.72478E−9f′(u3)=24⋅0.17364…2−6=−5.27631…u4=0.17364…
Δu4=∣0.17364…−0.17364…∣=1.085E−9Δu4=1.085E−9
u≈0.17364…
긴 나눗셈 적용:u−0.17364…8u3−6u+1=8u2+1.38918…u−5.75877…
8u2+1.38918…u−5.75877…≈0
다음을 위한 하나의 솔루션 찾기 8u2+1.38918…u−5.75877…=0 뉴턴-랩슨을 이용하여:u≈0.76604…
8u2+1.38918…u−5.75877…=0
뉴턴-랩슨 근사 정의
f(u)=8u2+1.38918…u−5.75877…
f′(u)찾다 :16u+1.38918…
dud(8u2+1.38918…u−5.75877…)
합계/차이 규칙 적용: (f±g)′=f′±g′=dud(8u2)+dud(1.38918…u)−dud(5.75877…)
dud(8u2)=16u
dud(8u2)
정수를 빼라: (a⋅f)′=a⋅f′=8dud(u2)
전원 규칙을 적용합니다: dxd(xa)=a⋅xa−1=8⋅2u2−1
단순화=16u
dud(1.38918…u)=1.38918…
dud(1.38918…u)
정수를 빼라: (a⋅f)′=a⋅f′=1.38918…dudu
공통 도함수 적용: dudu=1=1.38918…⋅1
단순화=1.38918…
dud(5.75877…)=0
dud(5.75877…)
상수의 도함수: dxd(a)=0=0
=16u+1.38918…−0
단순화=16u+1.38918…
렛 u0=4계산하다 un+1 까지 Δun+1<0.000001
u1=2.04557…:Δu1=1.95442…
f(u0)=8⋅42+1.38918…⋅4−5.75877…=127.79797…f′(u0)=16⋅4+1.38918…=65.38918…u1=2.04557…
Δu1=∣2.04557…−4∣=1.95442…Δu1=1.95442…
u2=1.14993…:Δu2=0.89564…
f(u1)=8⋅2.04557…2+1.38918…⋅2.04557…−5.75877…=30.55807…f′(u1)=16⋅2.04557…+1.38918…=34.11845…u2=1.14993…
Δu2=∣1.14993…−2.04557…∣=0.89564…Δu2=0.89564…
u3=0.82562…:Δu3=0.32430…
f(u2)=8⋅1.14993…2+1.38918…⋅1.14993…−5.75877…=6.41746…f′(u2)=16⋅1.14993…+1.38918…=19.78811…u3=0.82562…
Δu3=∣0.82562…−1.14993…∣=0.32430…Δu3=0.32430…
u4=0.76798…:Δu4=0.05763…
f(u3)=8⋅0.82562…2+1.38918…⋅0.82562…−5.75877…=0.84141…f′(u3)=16⋅0.82562…+1.38918…=14.59916…u4=0.76798…
Δu4=∣0.76798…−0.82562…∣=0.05763…Δu4=0.05763…
u5=0.76604…:Δu5=0.00194…
f(u4)=8⋅0.76798…2+1.38918…⋅0.76798…−5.75877…=0.02657…f′(u4)=16⋅0.76798…+1.38918…=13.67701…u5=0.76604…
Δu5=∣0.76604…−0.76798…∣=0.00194…Δu5=0.00194…
u6=0.76604…:Δu6=2.21312E−6
f(u5)=8⋅0.76604…2+1.38918…⋅0.76604…−5.75877…=0.00003…f′(u5)=16⋅0.76604…+1.38918…=13.64593…u6=0.76604…
Δu6=∣0.76604…−0.76604…∣=2.21312E−6Δu6=2.21312E−6
u7=0.76604…:Δu7=2.87147E−12
f(u6)=8⋅0.76604…2+1.38918…⋅0.76604…−5.75877…=3.91838E−11f′(u6)=16⋅0.76604…+1.38918…=13.64589…u7=0.76604…
Δu7=∣0.76604…−0.76604…∣=2.87147E−12Δu7=2.87147E−12
u≈0.76604…
긴 나눗셈 적용:u−0.76604…8u2+1.38918…u−5.75877…=8u+7.51754…
8u+7.51754…≈0
u≈−0.93969…
해결책은u≈0.17364…,u≈0.76604…,u≈−0.93969…
뒤로 대체 u=sin(x)sin(x)≈0.17364…,sin(x)≈0.76604…,sin(x)≈−0.93969…
sin(x)≈0.17364…,sin(x)≈0.76604…,sin(x)≈−0.93969…
sin(x)=0.17364…:x=arcsin(0.17364…)+2πn,x=π−arcsin(0.17364…)+2πn
sin(x)=0.17364…
트리거 역속성 적용
sin(x)=0.17364…
일반 솔루션 sin(x)=0.17364…sin(x)=a⇒x=arcsin(a)+2πn,x=π−arcsin(a)+2πnx=arcsin(0.17364…)+2πn,x=π−arcsin(0.17364…)+2πn
x=arcsin(0.17364…)+2πn,x=π−arcsin(0.17364…)+2πn
sin(x)=0.76604…:x=arcsin(0.76604…)+2πn,x=π−arcsin(0.76604…)+2πn
sin(x)=0.76604…
트리거 역속성 적용
sin(x)=0.76604…
일반 솔루션 sin(x)=0.76604…sin(x)=a⇒x=arcsin(a)+2πn,x=π−arcsin(a)+2πnx=arcsin(0.76604…)+2πn,x=π−arcsin(0.76604…)+2πn
x=arcsin(0.76604…)+2πn,x=π−arcsin(0.76604…)+2πn
sin(x)=−0.93969…:x=arcsin(−0.93969…)+2πn,x=π+arcsin(0.93969…)+2πn
sin(x)=−0.93969…
트리거 역속성 적용
sin(x)=−0.93969…
일반 솔루션 sin(x)=−0.93969…sin(x)=−a⇒x=arcsin(−a)+2πn,x=π+arcsin(a)+2πnx=arcsin(−0.93969…)+2πn,x=π+arcsin(0.93969…)+2πn
x=arcsin(−0.93969…)+2πn,x=π+arcsin(0.93969…)+2πn
모든 솔루션 결합x=arcsin(0.17364…)+2πn,x=π−arcsin(0.17364…)+2πn,x=arcsin(0.76604…)+2πn,x=π−arcsin(0.76604…)+2πn,x=arcsin(−0.93969…)+2πn,x=π+arcsin(0.93969…)+2πn
해를 10진수 형식으로 표시x=0.17453…+2πn,x=π−0.17453…+2πn,x=0.87266…+2πn,x=π−0.87266…+2πn,x=−1.22173…+2πn,x=π+1.22173…+2πn