해법
sin4(x)=−cos(x)
해법
x=π−1.01821…+2πn,x=π+1.01821…+2πn
+1
도
x=121.66074…∘+360∘n,x=238.33925…∘+360∘n솔루션 단계
sin4(x)=−cos(x)
양쪽을 제곱(sin4(x))2=(−cos(x))2
빼다 (−cos(x))2 양쪽에서sin8(x)−cos2(x)=0
삼각성을 사용하여 다시 쓰기
−cos2(x)+sin8(x)
피타고라스 정체성 사용: cos2(x)+sin2(x)=1cos2(x)=1−sin2(x)=−(1−sin2(x))+sin8(x)
−(1−sin2(x)):−1+sin2(x)
−(1−sin2(x))
괄호 배포=−(1)−(−sin2(x))
마이너스 플러스 규칙 적용−(−a)=a,−(a)=−a=−1+sin2(x)
=−1+sin2(x)+sin8(x)
−1+sin2(x)+sin8(x)=0
대체로 해결
−1+sin2(x)+sin8(x)=0
하게: sin(x)=u−1+u2+u8=0
−1+u2+u8=0:u=0.72449…,u=−0.72449…
−1+u2+u8=0
표준 양식으로 작성 anxn+…+a1x+a0=0u8+u2−1=0
다음으로 방정식 다시 쓰기 v=u2 그리고 v4=u8v4+v−1=0
v4+v−1=0해결 :v≈0.72449…,v≈−1.22074…
v4+v−1=0
다음을 위한 하나의 솔루션 찾기 v4+v−1=0 뉴턴-랩슨을 이용하여:v≈0.72449…
v4+v−1=0
뉴턴-랩슨 근사 정의
f(v)=v4+v−1
f′(v)찾다 :4v3+1
dvd(v4+v−1)
합계/차이 규칙 적용: (f±g)′=f′±g′=dvd(v4)+dvdv−dvd(1)
dvd(v4)=4v3
dvd(v4)
전원 규칙을 적용합니다: dxd(xa)=a⋅xa−1=4v4−1
단순화=4v3
dvdv=1
dvdv
공통 도함수 적용: dvdv=1=1
dvd(1)=0
dvd(1)
상수의 도함수: dxd(a)=0=0
=4v3+1−0
단순화=4v3+1
렛 v0=1계산하다 vn+1 까지 Δvn+1<0.000001
v1=0.8:Δv1=0.2
f(v0)=14+1−1=1f′(v0)=4⋅13+1=5v1=0.8
Δv1=∣0.8−1∣=0.2Δv1=0.2
v2=0.73123…:Δv2=0.06876…
f(v1)=0.84+0.8−1=0.2096f′(v1)=4⋅0.83+1=3.048v2=0.73123…
Δv2=∣0.73123…−0.8∣=0.06876…Δv2=0.06876…
v3=0.72454…:Δv3=0.00668…
f(v2)=0.73123…4+0.73123…−1=0.01714…f′(v2)=4⋅0.73123…3+1=2.56396…v3=0.72454…
Δv3=∣0.72454…−0.73123…∣=0.00668…Δv3=0.00668…
v4=0.72449…:Δv4=0.00005…
f(v3)=0.72454…4+0.72454…−1=0.00014…f′(v3)=4⋅0.72454…3+1=2.52146…v4=0.72449…
Δv4=∣0.72449…−0.72454…∣=0.00005…Δv4=0.00005…
v5=0.72449…:Δv5=3.99053E−9
f(v4)=0.72449…4+0.72449…−1=1.00606E−8f′(v4)=4⋅0.72449…3+1=2.52111…v5=0.72449…
Δv5=∣0.72449…−0.72449…∣=3.99053E−9Δv5=3.99053E−9
v≈0.72449…
긴 나눗셈 적용:v−0.72449…v4+v−1=v3+0.72449…v2+0.52488…v+1.38027…
v3+0.72449…v2+0.52488…v+1.38027…≈0
다음을 위한 하나의 솔루션 찾기 v3+0.72449…v2+0.52488…v+1.38027…=0 뉴턴-랩슨을 이용하여:v≈−1.22074…
v3+0.72449…v2+0.52488…v+1.38027…=0
뉴턴-랩슨 근사 정의
f(v)=v3+0.72449…v2+0.52488…v+1.38027…
f′(v)찾다 :3v2+1.44898…v+0.52488…
dvd(v3+0.72449…v2+0.52488…v+1.38027…)
합계/차이 규칙 적용: (f±g)′=f′±g′=dvd(v3)+dvd(0.72449…v2)+dvd(0.52488…v)+dvd(1.38027…)
dvd(v3)=3v2
dvd(v3)
전원 규칙을 적용합니다: dxd(xa)=a⋅xa−1=3v3−1
단순화=3v2
dvd(0.72449…v2)=1.44898…v
dvd(0.72449…v2)
정수를 빼라: (a⋅f)′=a⋅f′=0.72449…dvd(v2)
전원 규칙을 적용합니다: dxd(xa)=a⋅xa−1=0.72449…⋅2v2−1
단순화=1.44898…v
dvd(0.52488…v)=0.52488…
dvd(0.52488…v)
정수를 빼라: (a⋅f)′=a⋅f′=0.52488…dvdv
공통 도함수 적용: dvdv=1=0.52488…⋅1
단순화=0.52488…
dvd(1.38027…)=0
dvd(1.38027…)
상수의 도함수: dxd(a)=0=0
=3v2+1.44898…v+0.52488…+0
단순화=3v2+1.44898…v+0.52488…
렛 v0=−3계산하다 vn+1 까지 Δvn+1<0.000001
v1=−2.10803…:Δv1=0.89196…
f(v0)=(−3)3+0.72449…(−3)2+0.52488…(−3)+1.38027…=−20.67396…f′(v0)=3(−3)2+1.44898…(−3)+0.52488…=23.17793…v1=−2.10803…
Δv1=∣−2.10803…−(−3)∣=0.89196…Δv1=0.89196…
v2=−1.56419…:Δv2=0.54383…
f(v1)=(−2.10803…)3+0.72449…(−2.10803…)2+0.52488…(−2.10803…)+1.38027…=−5.87438…f′(v1)=3(−2.10803…)2+1.44898…(−2.10803…)+0.52488…=10.80178…v2=−1.56419…
Δv2=∣−1.56419…−(−2.10803…)∣=0.54383…Δv2=0.54383…
v3=−1.29711…:Δv3=0.26708…
f(v2)=(−1.56419…)3+0.72449…(−1.56419…)2+0.52488…(−1.56419…)+1.38027…=−1.49527…f′(v2)=3(−1.56419…)2+1.44898…(−1.56419…)+0.52488…=5.59853…v3=−1.29711…
Δv3=∣−1.29711…−(−1.56419…)∣=0.26708…Δv3=0.26708…
v4=−1.22562…:Δv4=0.07148…
f(v3)=(−1.29711…)3+0.72449…(−1.29711…)2+0.52488…(−1.29711…)+1.38027…=−0.26400…f′(v3)=3(−1.29711…)2+1.44898…(−1.29711…)+0.52488…=3.69291…v4=−1.22562…
Δv4=∣−1.22562…−(−1.29711…)∣=0.07148…Δv4=0.07148…
v5=−1.22076…:Δv5=0.00485…
f(v4)=(−1.22562…)3+0.72449…(−1.22562…)2+0.52488…(−1.22562…)+1.38027…=−0.01581…f′(v4)=3(−1.22562…)2+1.44898…(−1.22562…)+0.52488…=3.25544…v5=−1.22076…
Δv5=∣−1.22076…−(−1.22562…)∣=0.00485…Δv5=0.00485…
v6=−1.22074…:Δv6=0.00002…
f(v5)=(−1.22076…)3+0.72449…(−1.22076…)2+0.52488…(−1.22076…)+1.38027…=−0.00006…f′(v5)=3(−1.22076…)2+1.44898…(−1.22076…)+0.52488…=3.22682…v6=−1.22074…
Δv6=∣−1.22074…−(−1.22076…)∣=0.00002…Δv6=0.00002…
v7=−1.22074…:Δv7=4.23633E−10
f(v6)=(−1.22074…)3+0.72449…(−1.22074…)2+0.52488…(−1.22074…)+1.38027…=−1.36693E−9f′(v6)=3(−1.22074…)2+1.44898…(−1.22074…)+0.52488…=3.22669…v7=−1.22074…
Δv7=∣−1.22074…−(−1.22074…)∣=4.23633E−10Δv7=4.23633E−10
v≈−1.22074…
긴 나눗셈 적용:v+1.22074…v3+0.72449…v2+0.52488…v+1.38027…=v2−0.49625…v+1.13068…
v2−0.49625…v+1.13068…≈0
다음을 위한 하나의 솔루션 찾기 v2−0.49625…v+1.13068…=0 뉴턴-랩슨을 이용하여:솔루션 없음 v∈R
v2−0.49625…v+1.13068…=0
뉴턴-랩슨 근사 정의
f(v)=v2−0.49625…v+1.13068…
f′(v)찾다 :2v−0.49625…
dvd(v2−0.49625…v+1.13068…)
합계/차이 규칙 적용: (f±g)′=f′±g′=dvd(v2)−dvd(0.49625…v)+dvd(1.13068…)
dvd(v2)=2v
dvd(v2)
전원 규칙을 적용합니다: dxd(xa)=a⋅xa−1=2v2−1
단순화=2v
dvd(0.49625…v)=0.49625…
dvd(0.49625…v)
정수를 빼라: (a⋅f)′=a⋅f′=0.49625…dvdv
공통 도함수 적용: dvdv=1=0.49625…⋅1
단순화=0.49625…
dvd(1.13068…)=0
dvd(1.13068…)
상수의 도함수: dxd(a)=0=0
=2v−0.49625…+0
단순화=2v−0.49625…
렛 v0=2계산하다 vn+1 까지 Δvn+1<0.000001
v1=0.81892…:Δv1=1.18107…
f(v0)=22−0.49625…⋅2+1.13068…=4.13818…f′(v0)=2⋅2−0.49625…=3.50374…v1=0.81892…
Δv1=∣0.81892…−2∣=1.18107…Δv1=1.18107…
v2=−0.40298…:Δv2=1.22190…
f(v1)=0.81892…2−0.49625…⋅0.81892…+1.13068…=1.39493…f′(v1)=2⋅0.81892…−0.49625…=1.14160…v2=−0.40298…
Δv2=∣−0.40298…−0.81892…∣=1.22190…Δv2=1.22190…
v3=0.74357…:Δv3=1.14655…
f(v2)=(−0.40298…)2−0.49625…(−0.40298…)+1.13068…=1.49305…f′(v2)=2(−0.40298…)−0.49625…=−1.30221…v3=0.74357…
Δv3=∣0.74357…−(−0.40298…)∣=1.14655…Δv3=1.14655…
v4=−0.58309…:Δv4=1.32666…
f(v3)=0.74357…2−0.49625…⋅0.74357…+1.13068…=1.31458…f′(v3)=2⋅0.74357…−0.49625…=0.99089…v4=−0.58309…
Δv4=∣−0.58309…−0.74357…∣=1.32666…Δv4=1.32666…
v5=0.47562…:Δv5=1.05871…
f(v4)=(−0.58309…)2−0.49625…(−0.58309…)+1.13068…=1.76004…f′(v4)=2(−0.58309…)−0.49625…=−1.66243…v5=0.47562…
Δv5=∣0.47562…−(−0.58309…)∣=1.05871…Δv5=1.05871…
v6=−1.98788…:Δv6=2.46350…
f(v5)=0.47562…2−0.49625…⋅0.47562…+1.13068…=1.12087…f′(v5)=2⋅0.47562…−0.49625…=0.45499…v6=−1.98788…
Δv6=∣−1.98788…−0.47562…∣=2.46350…Δv6=2.46350…
v7=−0.63081…:Δv7=1.35707…
f(v6)=(−1.98788…)2−0.49625…(−1.98788…)+1.13068…=6.06887…f′(v6)=2(−1.98788…)−0.49625…=−4.47202…v7=−0.63081…
Δv7=∣−0.63081…−(−1.98788…)∣=1.35707…Δv7=1.35707…
v8=0.41684…:Δv8=1.04765…
f(v7)=(−0.63081…)2−0.49625…(−0.63081…)+1.13068…=1.84165…f′(v7)=2(−0.63081…)−0.49625…=−1.75787…v8=0.41684…
Δv8=∣0.41684…−(−0.63081…)∣=1.04765…Δv8=1.04765…
v9=−2.83587…:Δv9=3.25272…
f(v8)=0.41684…2−0.49625…⋅0.41684…+1.13068…=1.09758…f′(v8)=2⋅0.41684…−0.49625…=0.33743…v9=−2.83587…
Δv9=∣−2.83587…−0.41684…∣=3.25272…Δv9=3.25272…
해결 방법을 찾을 수 없습니다
해결책은v≈0.72449…,v≈−1.22074…
v≈0.72449…,v≈−1.22074…
다시 대체 v=u2,을 해결하다 u
u2=0.72449…해결 :u=0.72449…,u=−0.72449…
u2=0.72449…
위해서 x2=f(a) 해결책은 x=f(a),−f(a)
u=0.72449…,u=−0.72449…
u2=−1.22074…해결 :솔루션 없음 u∈R
u2=−1.22074…
x2 에 부정적일 수는 없다 x∈R솔루션없음u∈R
해결책은
u=0.72449…,u=−0.72449…
뒤로 대체 u=sin(x)sin(x)=0.72449…,sin(x)=−0.72449…
sin(x)=0.72449…,sin(x)=−0.72449…
sin(x)=0.72449…:x=arcsin(0.72449…)+2πn,x=π−arcsin(0.72449…)+2πn
sin(x)=0.72449…
트리거 역속성 적용
sin(x)=0.72449…
일반 솔루션 sin(x)=0.72449…sin(x)=a⇒x=arcsin(a)+2πn,x=π−arcsin(a)+2πnx=arcsin(0.72449…)+2πn,x=π−arcsin(0.72449…)+2πn
x=arcsin(0.72449…)+2πn,x=π−arcsin(0.72449…)+2πn
sin(x)=−0.72449…:x=arcsin(−0.72449…)+2πn,x=π+arcsin(0.72449…)+2πn
sin(x)=−0.72449…
트리거 역속성 적용
sin(x)=−0.72449…
일반 솔루션 sin(x)=−0.72449…sin(x)=−a⇒x=arcsin(−a)+2πn,x=π+arcsin(a)+2πnx=arcsin(−0.72449…)+2πn,x=π+arcsin(0.72449…)+2πn
x=arcsin(−0.72449…)+2πn,x=π+arcsin(0.72449…)+2πn
모든 솔루션 결합x=arcsin(0.72449…)+2πn,x=π−arcsin(0.72449…)+2πn,x=arcsin(−0.72449…)+2πn,x=π+arcsin(0.72449…)+2πn
해법을 원래 방정식에 연결하여 검증
솔루션을 에 연결하여 확인합니다 sin4(x)=−cos(x)
방정식에 맞지 않는 것은 제거하십시오.
솔루션 확인 arcsin(0.72449…)+2πn:거짓
arcsin(0.72449…)+2πn
n=1끼우다 arcsin(0.72449…)+2π1
sin4(x)=−cos(x) 위한 {\ quad}끼우다{\ quad} x=arcsin(0.72449…)+2π1sin4(arcsin(0.72449…)+2π1)=−cos(arcsin(0.72449…)+2π1)
다듬다0.52488…=−0.52488…
⇒거짓
솔루션 확인 π−arcsin(0.72449…)+2πn:참
π−arcsin(0.72449…)+2πn
n=1끼우다 π−arcsin(0.72449…)+2π1
sin4(x)=−cos(x) 위한 {\ quad}끼우다{\ quad} x=π−arcsin(0.72449…)+2π1sin4(π−arcsin(0.72449…)+2π1)=−cos(π−arcsin(0.72449…)+2π1)
다듬다0.52488…=0.52488…
⇒참
솔루션 확인 arcsin(−0.72449…)+2πn:거짓
arcsin(−0.72449…)+2πn
n=1끼우다 arcsin(−0.72449…)+2π1
sin4(x)=−cos(x) 위한 {\ quad}끼우다{\ quad} x=arcsin(−0.72449…)+2π1sin4(arcsin(−0.72449…)+2π1)=−cos(arcsin(−0.72449…)+2π1)
다듬다0.52488…=−0.52488…
⇒거짓
솔루션 확인 π+arcsin(0.72449…)+2πn:참
π+arcsin(0.72449…)+2πn
n=1끼우다 π+arcsin(0.72449…)+2π1
sin4(x)=−cos(x) 위한 {\ quad}끼우다{\ quad} x=π+arcsin(0.72449…)+2π1sin4(π+arcsin(0.72449…)+2π1)=−cos(π+arcsin(0.72449…)+2π1)
다듬다0.52488…=0.52488…
⇒참
x=π−arcsin(0.72449…)+2πn,x=π+arcsin(0.72449…)+2πn
해를 10진수 형식으로 표시x=π−1.01821…+2πn,x=π+1.01821…+2πn