해법
sin2(x)⋅cos(x)+1=0
해법
솔루션없음x∈R
솔루션 단계
sin2(x)cos(x)+1=0
삼각성을 사용하여 다시 쓰기
1+cos(x)sin2(x)
피타고라스 정체성 사용: cos2(x)+sin2(x)=1sin2(x)=1−cos2(x)=1+cos(x)(1−cos2(x))
1+(1−cos2(x))cos(x)=0
대체로 해결
1+(1−cos2(x))cos(x)=0
하게: cos(x)=u1+(1−u2)u=0
1+(1−u2)u=0:u≈1.32471…
1+(1−u2)u=0
1+(1−u2)u 확장 :1+u−u3
1+(1−u2)u
=1+u(1−u2)
u(1−u2)확대한다:u−u3
u(1−u2)
분배 법칙 적용: a(b−c)=ab−aca=u,b=1,c=u2=u⋅1−uu2
=1⋅u−u2u
1⋅u−u2u단순화하세요:u−u3
1⋅u−u2u
1⋅u=u
1⋅u
곱하다: 1⋅u=u=u
u2u=u3
u2u
지수 규칙 적용: ab⋅ac=ab+cu2u=u2+1=u2+1
숫자 추가: 2+1=3=u3
=u−u3
=u−u3
=1+u−u3
1+u−u3=0
표준 양식으로 작성 anxn+…+a1x+a0=0−u3+u+1=0
다음을 위한 하나의 솔루션 찾기 −u3+u+1=0 뉴턴-랩슨을 이용하여:u≈1.32471…
−u3+u+1=0
뉴턴-랩슨 근사 정의
f(u)=−u3+u+1
f′(u)찾다 :−3u2+1
dud(−u3+u+1)
합계/차이 규칙 적용: (f±g)′=f′±g′=−dud(u3)+dudu+dud(1)
dud(u3)=3u2
dud(u3)
전원 규칙을 적용합니다: dxd(xa)=a⋅xa−1=3u3−1
단순화=3u2
dudu=1
dudu
공통 도함수 적용: dudu=1=1
dud(1)=0
dud(1)
상수의 도함수: dxd(a)=0=0
=−3u2+1+0
단순화=−3u2+1
렛 u0=1계산하다 un+1 까지 Δun+1<0.000001
u1=1.5:Δu1=0.5
f(u0)=−13+1+1=1f′(u0)=−3⋅12+1=−2u1=1.5
Δu1=∣1.5−1∣=0.5Δu1=0.5
u2=1.34782…:Δu2=0.15217…
f(u1)=−1.53+1.5+1=−0.875f′(u1)=−3⋅1.52+1=−5.75u2=1.34782…
Δu2=∣1.34782…−1.5∣=0.15217…Δu2=0.15217…
u3=1.32520…:Δu3=0.02262…
f(u2)=−1.34782…3+1.34782…+1=−0.10068…f′(u2)=−3⋅1.34782…2+1=−4.44990…u3=1.32520…
Δu3=∣1.32520…−1.34782…∣=0.02262…Δu3=0.02262…
u4=1.32471…:Δu4=0.00048…
f(u3)=−1.32520…3+1.32520…+1=−0.00205…f′(u3)=−3⋅1.32520…2+1=−4.26846…u4=1.32471…
Δu4=∣1.32471…−1.32520…∣=0.00048…Δu4=0.00048…
u5=1.32471…:Δu5=2.16754E−7
f(u4)=−1.32471…3+1.32471…+1=−9.24378E−7f′(u4)=−3⋅1.32471…2+1=−4.26463…u5=1.32471…
Δu5=∣1.32471…−1.32471…∣=2.16754E−7Δu5=2.16754E−7
u≈1.32471…
긴 나눗셈 적용:u−1.32471…−u3+u+1=−u2−1.32471…u−0.75487…
−u2−1.32471…u−0.75487…≈0
다음을 위한 하나의 솔루션 찾기 −u2−1.32471…u−0.75487…=0 뉴턴-랩슨을 이용하여:솔루션 없음 u∈R
−u2−1.32471…u−0.75487…=0
뉴턴-랩슨 근사 정의
f(u)=−u2−1.32471…u−0.75487…
f′(u)찾다 :−2u−1.32471…
dud(−u2−1.32471…u−0.75487…)
합계/차이 규칙 적용: (f±g)′=f′±g′=−dud(u2)−dud(1.32471…u)−dud(0.75487…)
dud(u2)=2u
dud(u2)
전원 규칙을 적용합니다: dxd(xa)=a⋅xa−1=2u2−1
단순화=2u
dud(1.32471…u)=1.32471…
dud(1.32471…u)
정수를 빼라: (a⋅f)′=a⋅f′=1.32471…dudu
공통 도함수 적용: dudu=1=1.32471…⋅1
단순화=1.32471…
dud(0.75487…)=0
dud(0.75487…)
상수의 도함수: dxd(a)=0=0
=−2u−1.32471…−0
단순화=−2u−1.32471…
렛 u0=−1계산하다 un+1 까지 Δun+1<0.000001
u1=−0.36299…:Δu1=0.63700…
f(u0)=−(−1)2−1.32471…(−1)−0.75487…=−0.43015…f′(u0)=−2(−1)−1.32471…=0.67528…u1=−0.36299…
Δu1=∣−0.36299…−(−1)∣=0.63700…Δu1=0.63700…
u2=−1.04072…:Δu2=0.67772…
f(u1)=−(−0.36299…)2−1.32471…(−0.36299…)−0.75487…=−0.40577…f′(u1)=−2(−0.36299…)−1.32471…=−0.59873…u2=−1.04072…
Δu2=∣−1.04072…−(−0.36299…)∣=0.67772…Δu2=0.67772…
u3=−0.43374…:Δu3=0.60697…
f(u2)=−(−1.04072…)2−1.32471…(−1.04072…)−0.75487…=−0.45931…f′(u2)=−2(−1.04072…)−1.32471…=0.75672…u3=−0.43374…
Δu3=∣−0.43374…−(−1.04072…)∣=0.60697…Δu3=0.60697…
u4=−1.23950…:Δu4=0.80576…
f(u3)=−(−0.43374…)2−1.32471…(−0.43374…)−0.75487…=−0.36842…f′(u3)=−2(−0.43374…)−1.32471…=−0.45723…u4=−1.23950…
Δu4=∣−1.23950…−(−0.43374…)∣=0.80576…Δu4=0.80576…
u5=−0.67703…:Δu5=0.56247…
f(u4)=−(−1.23950…)2−1.32471…(−1.23950…)−0.75487…=−0.64925…f′(u4)=−2(−1.23950…)−1.32471…=1.15429…u5=−0.67703…
Δu5=∣−0.67703…−(−1.23950…)∣=0.56247…Δu5=0.56247…
u6=10.09982…:Δu6=10.77686…
f(u5)=−(−0.67703…)2−1.32471…(−0.67703…)−0.75487…=−0.31637…f′(u5)=−2(−0.67703…)−1.32471…=0.02935…u6=10.09982…
Δu6=∣10.09982…−(−0.67703…)∣=10.77686…Δu6=10.77686…
u7=4.70404…:Δu7=5.39578…
f(u6)=−10.09982…2−1.32471…⋅10.09982…−0.75487…=−116.14080…f′(u6)=−2⋅10.09982…−1.32471…=−21.52437…u7=4.70404…
Δu7=∣4.70404…−10.09982…∣=5.39578…Δu7=5.39578…
u8=1.99138…:Δu8=2.71265…
f(u7)=−4.70404…2−1.32471…⋅4.70404…−0.75487…=−29.11445…f′(u7)=−2⋅4.70404…−1.32471…=−10.73280…u8=1.99138…
Δu8=∣1.99138…−4.70404…∣=2.71265…Δu8=2.71265…
u9=0.60494…:Δu9=1.38644…
f(u8)=−1.99138…2−1.32471…⋅1.99138…−0.75487…=−7.35852…f′(u8)=−2⋅1.99138…−1.32471…=−5.30749…u9=0.60494…
Δu9=∣0.60494…−1.99138…∣=1.38644…Δu9=1.38644…
u10=−0.15344…:Δu10=0.75838…
f(u9)=−0.60494…2−1.32471…⋅0.60494…−0.75487…=−1.92221…f′(u9)=−2⋅0.60494…−1.32471…=−2.53460…u10=−0.15344…
Δu10=∣−0.15344…−0.60494…∣=0.75838…Δu10=0.75838…
u11=−0.71852…:Δu11=0.56507…
f(u10)=−(−0.15344…)2−1.32471…(−0.15344…)−0.75487…=−0.57515…f′(u10)=−2(−0.15344…)−1.32471…=−1.01783…u11=−0.71852…
Δu11=∣−0.71852…−(−0.15344…)∣=0.56507…Δu11=0.56507…
u12=2.12427…:Δu12=2.84279…
f(u11)=−(−0.71852…)2−1.32471…(−0.71852…)−0.75487…=−0.31931…f′(u11)=−2(−0.71852…)−1.32471…=0.11232…u12=2.12427…
Δu12=∣2.12427…−(−0.71852…)∣=2.84279…Δu12=2.84279…
해결 방법을 찾을 수 없습니다
해결책은u≈1.32471…
뒤로 대체 u=cos(x)cos(x)≈1.32471…
cos(x)≈1.32471…
cos(x)=1.32471…:해결책 없음
cos(x)=1.32471…
−1≤cos(x)≤1해결책없음
모든 솔루션 결합솔루션없음x∈R