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人気のある三角関数 >

2cos(4x)=2cos^2(2x)-sin(2x)-1

解

2 cos (4 x) = 2 cos^{2} (2 x) - sin (2 x) - 1

解

x = \frac{7 π}{12} + πn, x = \frac{11 π}{12} + πn, x = \frac{π}{4} + πn

+1

度

x = 10 5^{\circ} + 18 0^{\circ} n, x = 16 5^{\circ} + 18 0^{\circ} n, x = 4 5^{\circ} + 18 0^{\circ} n

解答ステップ

2 cos (4 x) = 2 cos^{2} (2 x) - sin (2 x) - 1

両辺から

2 cos^{2} (2 x) - sin (2 x) - 1

を引く

2 cos (4 x) - 2 cos^{2} (2 x) + sin (2 x) + 1 = 0

三角関数の公式を使用して書き換える

1 + sin (2 x) - 2 cos^{2} (2 x) + 2 cos (4 x)

2倍角の公式を使用:

cos^{2} (x) - sin^{2} (x) = cos (2 x)

cos^{2} (x) = cos (2 x) + sin^{2} (x)

= 1 + sin (2 x) - 2 (cos (2 \cdot 2 x) + sin^{2} (2 x)) + 2 cos (4 x)

簡素化

1 + sin (2 x) - 2 (cos (2 \cdot 2 x) + sin^{2} (2 x)) + 2 cos (4 x) : sin (2 x) - 2 sin^{2} (2 x) + 1

1 + sin (2 x) - 2 (cos (2 \cdot 2 x) + sin^{2} (2 x)) + 2 cos (4 x)

数を乗じる:

2 \cdot 2 = 4

= 1 + sin (2 x) - 2 (sin^{2} (2 x) + cos (4 x)) + 2 cos (4 x)

拡張

- 2 (cos (4 x) + sin^{2} (2 x)) : - 2 cos (4 x) - 2 sin^{2} (2 x)

- 2 (cos (4 x) + sin^{2} (2 x))

分配法則を適用する:

a (b + c) = ab + a c

a = - 2, b = cos (4 x), c = sin^{2} (2 x)

= - 2 cos (4 x) + (- 2) sin^{2} (2 x)

マイナス・プラスの規則を適用する

+ (- a) = - a

= - 2 cos (4 x) - 2 sin^{2} (2 x)

= 1 + sin (2 x) - 2 cos (4 x) - 2 sin^{2} (2 x) + 2 cos (4 x)

簡素化

1 + sin (2 x) - 2 cos (4 x) - 2 sin^{2} (2 x) + 2 cos (4 x) : sin (2 x) - 2 sin^{2} (2 x) + 1

1 + sin (2 x) - 2 cos (4 x) - 2 sin^{2} (2 x) + 2 cos (4 x)

条件のようなグループ

= sin (2 x) - 2 cos (4 x) - 2 sin^{2} (2 x) + 2 cos (4 x) + 1

類似した元を足す:

- 2 cos (4 x) + 2 cos (4 x) = 0

= sin (2 x) - 2 sin^{2} (2 x) + 1

= sin (2 x) - 2 sin^{2} (2 x) + 1

= sin (2 x) - 2 sin^{2} (2 x) + 1

1 + sin (2 x) - 2 sin^{2} (2 x) = 0

置換で解く

1 + sin (2 x) - 2 sin^{2} (2 x) = 0

仮定:

sin (2 x) = u

1 + u - 2 u^{2} = 0

1 + u - 2 u^{2} = 0 : u = - \frac{1}{2}, u = 1

1 + u - 2 u^{2} = 0

標準的な形式で書く

a x^{2} + b x + c = 0

- 2 u^{2} + u + 1 = 0

解くとthe二次式

- 2 u^{2} + u + 1 = 0

二次Equationの公式:

次の場合:

a = - 2, b = 1, c = 1

u_{1, 2} = \frac{- 1 \pm 1 ^{2} - 4 ( - 2 ) \cdot 1}{2 ( - 2 )}

u_{1, 2} = \frac{- 1 \pm 1 ^{2} - 4 ( - 2 ) \cdot 1}{2 ( - 2 )}

1^{2} - 4 (- 2) \cdot 1 = 3

1^{2} - 4 (- 2) \cdot 1

規則を適用

1^{a} = 1

1^{2} = 1

= 1 - 4 (- 2) \cdot 1

規則を適用

- (- a) = a

= 1 + 4 \cdot 2 \cdot 1

数を乗じる:

4 \cdot 2 \cdot 1 = 8

= 1 + 8

数を足す:

1 + 8 = 9

= 9

数を因数に分解する:

9 = 3^{2}

= 3^{2}

累乗根の規則を適用する:

n a^{n} = a

3^{2} = 3

= 3

u_{1, 2} = \frac{- 1 \pm 3}{2 ( - 2 )}

解を分離する

u_{1} = \frac{- 1 + 3}{2 ( - 2 )}, u_{2} = \frac{- 1 - 3}{2 ( - 2 )}

u = \frac{- 1 + 3}{2 ( - 2 )} : - \frac{1}{2}

\frac{- 1 + 3}{2 ( - 2 )}

括弧を削除する:

(- a) = - a

= \frac{- 1 + 3}{- 2 \cdot 2}

数を足す/引く:

- 1 + 3 = 2

= \frac{2}{- 2 \cdot 2}

数を乗じる:

2 \cdot 2 = 4

= \frac{2}{- 4}

分数の規則を適用する:

\frac{a}{- b} = - \frac{a}{b}

= - \frac{2}{4}

共通因数を約分する:

2

= - \frac{1}{2}

u = \frac{- 1 - 3}{2 ( - 2 )} : 1

\frac{- 1 - 3}{2 ( - 2 )}

括弧を削除する:

(- a) = - a

= \frac{- 1 - 3}{- 2 \cdot 2}

数を引く:

- 1 - 3 = - 4

= \frac{- 4}{- 2 \cdot 2}

数を乗じる:

2 \cdot 2 = 4

= \frac{- 4}{- 4}

分数の規則を適用する:

\frac{- a}{- b} = \frac{a}{b}

= \frac{4}{4}

規則を適用

\frac{a}{a} = 1

= 1

二次equationの解:

u = - \frac{1}{2}, u = 1

代用を戻す

u = sin (2 x)

sin (2 x) = - \frac{1}{2}, sin (2 x) = 1

sin (2 x) = - \frac{1}{2}, sin (2 x) = 1

sin (2 x) = - \frac{1}{2} : x = \frac{7 π}{12} + πn, x = \frac{11 π}{12} + πn

sin (2 x) = - \frac{1}{2}

以下の一般解

sin (2 x) = - \frac{1}{2}

sin (x)

2 πn

循環を含む周期性テーブル:

x 0 \frac{π}{6} \frac{π}{4} \frac{π}{3} \frac{π}{2} \frac{2 π}{3} \frac{3 π}{4} \frac{5 π}{6} sin (x) 0 \frac{1}{2} \frac{2}{2} \frac{3}{2} 1 \frac{3}{2} \frac{2}{2} \frac{1}{2} x π \frac{7 π}{6} \frac{5 π}{4} \frac{4 π}{3} \frac{3 π}{2} \frac{5 π}{3} \frac{7 π}{4} \frac{11 π}{6} sin (x) 0 - \frac{1}{2} - \frac{2}{2} - \frac{3}{2} - 1 - \frac{3}{2} - \frac{2}{2} - \frac{1}{2}

2 x = \frac{7 π}{6} + 2 πn, 2 x = \frac{11 π}{6} + 2 πn

2 x = \frac{7 π}{6} + 2 πn, 2 x = \frac{11 π}{6} + 2 πn

解く

2 x = \frac{7 π}{6} + 2 πn : x = \frac{7 π}{12} + πn

2 x = \frac{7 π}{6} + 2 πn

以下で両辺を割る

2

2 x = \frac{7 π}{6} + 2 πn

以下で両辺を割る

2

\frac{2 x}{2} = \frac{\frac{7 π}{6}}{2} + \frac{2 πn}{2}

簡素化

\frac{2 x}{2} = \frac{\frac{7 π}{6}}{2} + \frac{2 πn}{2}

簡素化

\frac{2 x}{2} : x

\frac{2 x}{2}

数を割る:

\frac{2}{2} = 1

= x

簡素化

\frac{\frac{7 π}{6}}{2} + \frac{2 πn}{2} : \frac{7 π}{12} + πn

\frac{\frac{7 π}{6}}{2} + \frac{2 πn}{2}

\frac{\frac{7 π}{6}}{2} = \frac{7 π}{12}

\frac{\frac{7 π}{6}}{2}

分数の規則を適用する:

\frac{\frac{b}{c}}{a} = \frac{b}{c \cdot a}

= \frac{7 π}{6 \cdot 2}

数を乗じる:

6 \cdot 2 = 12

= \frac{7 π}{12}

\frac{2 πn}{2} = πn

\frac{2 πn}{2}

数を割る:

\frac{2}{2} = 1

= πn

= \frac{7 π}{12} + πn

x = \frac{7 π}{12} + πn

x = \frac{7 π}{12} + πn

x = \frac{7 π}{12} + πn

解く

2 x = \frac{11 π}{6} + 2 πn : x = \frac{11 π}{12} + πn

2 x = \frac{11 π}{6} + 2 πn

以下で両辺を割る

2

2 x = \frac{11 π}{6} + 2 πn

以下で両辺を割る

2

\frac{2 x}{2} = \frac{\frac{11 π}{6}}{2} + \frac{2 πn}{2}

簡素化

\frac{2 x}{2} = \frac{\frac{11 π}{6}}{2} + \frac{2 πn}{2}

簡素化

\frac{2 x}{2} : x

\frac{2 x}{2}

数を割る:

\frac{2}{2} = 1

= x

簡素化

\frac{\frac{11 π}{6}}{2} + \frac{2 πn}{2} : \frac{11 π}{12} + πn

\frac{\frac{11 π}{6}}{2} + \frac{2 πn}{2}

\frac{\frac{11 π}{6}}{2} = \frac{11 π}{12}

\frac{\frac{11 π}{6}}{2}

分数の規則を適用する:

\frac{\frac{b}{c}}{a} = \frac{b}{c \cdot a}

= \frac{11 π}{6 \cdot 2}

数を乗じる:

6 \cdot 2 = 12

= \frac{11 π}{12}

\frac{2 πn}{2} = πn

\frac{2 πn}{2}

数を割る:

\frac{2}{2} = 1

= πn

= \frac{11 π}{12} + πn

x = \frac{11 π}{12} + πn

x = \frac{11 π}{12} + πn

x = \frac{11 π}{12} + πn

x = \frac{7 π}{12} + πn, x = \frac{11 π}{12} + πn

sin (2 x) = 1 : x = \frac{π}{4} + πn

sin (2 x) = 1

以下の一般解

sin (2 x) = 1

sin (x)

2 πn

循環を含む周期性テーブル:

x 0 \frac{π}{6} \frac{π}{4} \frac{π}{3} \frac{π}{2} \frac{2 π}{3} \frac{3 π}{4} \frac{5 π}{6} sin (x) 0 \frac{1}{2} \frac{2}{2} \frac{3}{2} 1 \frac{3}{2} \frac{2}{2} \frac{1}{2} x π \frac{7 π}{6} \frac{5 π}{4} \frac{4 π}{3} \frac{3 π}{2} \frac{5 π}{3} \frac{7 π}{4} \frac{11 π}{6} sin (x) 0 - \frac{1}{2} - \frac{2}{2} - \frac{3}{2} - 1 - \frac{3}{2} - \frac{2}{2} - \frac{1}{2}

2 x = \frac{π}{2} + 2 πn

2 x = \frac{π}{2} + 2 πn

解く

2 x = \frac{π}{2} + 2 πn : x = \frac{π}{4} + πn

2 x = \frac{π}{2} + 2 πn

以下で両辺を割る

2

2 x = \frac{π}{2} + 2 πn

以下で両辺を割る

2

\frac{2 x}{2} = \frac{\frac{π}{2}}{2} + \frac{2 πn}{2}

簡素化

\frac{2 x}{2} = \frac{\frac{π}{2}}{2} + \frac{2 πn}{2}

簡素化

\frac{2 x}{2} : x

\frac{2 x}{2}

数を割る:

\frac{2}{2} = 1

= x

簡素化

\frac{\frac{π}{2}}{2} + \frac{2 πn}{2} : \frac{π}{4} + πn

\frac{\frac{π}{2}}{2} + \frac{2 πn}{2}

\frac{\frac{π}{2}}{2} = \frac{π}{4}

\frac{\frac{π}{2}}{2}

分数の規則を適用する:

\frac{\frac{b}{c}}{a} = \frac{b}{c \cdot a}

= \frac{π}{2 \cdot 2}

数を乗じる:

2 \cdot 2 = 4

= \frac{π}{4}

\frac{2 πn}{2} = πn

\frac{2 πn}{2}

数を割る:

\frac{2}{2} = 1

= πn

= \frac{π}{4} + πn

x = \frac{π}{4} + πn

x = \frac{π}{4} + πn

x = \frac{π}{4} + πn

x = \frac{π}{4} + πn

すべての解を組み合わせる

x = \frac{7 π}{12} + πn, x = \frac{11 π}{12} + πn, x = \frac{π}{4} + πn

グラフ

人気の例

1 - sin^{2} (θ) = 0

2sin^2(x)+csc^2(x)=3

2 sin^{2} (x) + csc^{2} (x) = 3

sin (α) = \frac{8}{17}

2cosh^2(x)-3sinh(x)=1

2 cosh^{2} (x) - 3 sinh (x) = 1

solvefor x,y= 4/pi arccos(x/4)

so l v e f or x, y = \frac{4}{π} arccos (\frac{x}{4})