What is the general solution for sinh^2(x)=2sinh(x)cosh(x) ?

The general solution for sinh^2(x)=2sinh(x)cosh(x) is x=0

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sinh^2(x)=2sinh(x)cosh(x)

Solution

sinh^{2} (x) = 2 sinh (x) cosh (x)

Solution

x = 0

Degrees

x = 0^{\circ}

Solution steps

sinh^{2} (x) = 2 sinh (x) cosh (x)

Rewrite using trig identities

sinh^{2} (x) = 2 sinh (x) cosh (x)

Use the Hyperbolic identity:

sinh (x) = \frac{e ^{x} - e ^{- x}}{2}

(\frac{e ^{x} - e ^{- x}}{2})^{2} = 2 sinh (x) cosh (x)

Use the Hyperbolic identity:

sinh (x) = \frac{e ^{x} - e ^{- x}}{2}

(\frac{e ^{x} - e ^{- x}}{2})^{2} = 2 \cdot \frac{e ^{x} - e ^{- x}}{2} cosh (x)

Use the Hyperbolic identity:

cosh (x) = \frac{e ^{x} + e ^{- x}}{2}

(\frac{e ^{x} - e ^{- x}}{2})^{2} = 2 \cdot \frac{e ^{x} - e ^{- x}}{2} \cdot \frac{e ^{x} + e ^{- x}}{2}

(\frac{e ^{x} - e ^{- x}}{2})^{2} = 2 \cdot \frac{e ^{x} - e ^{- x}}{2} \cdot \frac{e ^{x} + e ^{- x}}{2}

(\frac{e ^{x} - e ^{- x}}{2})^{2} = 2 \cdot \frac{e ^{x} - e ^{- x}}{2} \cdot \frac{e ^{x} + e ^{- x}}{2} : x = 0

(\frac{e ^{x} - e ^{- x}}{2})^{2} = 2 \cdot \frac{e ^{x} - e ^{- x}}{2} \cdot \frac{e ^{x} + e ^{- x}}{2}

Apply exponent rules

(\frac{e ^{x} - e ^{- x}}{2})^{2} = 2 \cdot \frac{e ^{x} - e ^{- x}}{2} \cdot \frac{e ^{x} + e ^{- x}}{2}

Apply exponent rule:

a^{b c} = (a^{b})^{c}

e^{- x} = (e^{x})^{- 1}

(\frac{e ^{x} - ( e ^{x} ) ^{- 1}}{2})^{2} = 2 \cdot \frac{e ^{x} - ( e ^{x} ) ^{- 1}}{2} \cdot \frac{e ^{x} + ( e ^{x} ) ^{- 1}}{2}

(\frac{e ^{x} - ( e ^{x} ) ^{- 1}}{2})^{2} = 2 \cdot \frac{e ^{x} - ( e ^{x} ) ^{- 1}}{2} \cdot \frac{e ^{x} + ( e ^{x} ) ^{- 1}}{2}

Rewrite the equation with

e^{x} = u

(\frac{u - ( u ) ^{- 1}}{2})^{2} = 2 \cdot \frac{u - ( u ) ^{- 1}}{2} \cdot \frac{u + ( u ) ^{- 1}}{2}

Solve

(\frac{u - u ^{- 1}}{2})^{2} = 2 \cdot \frac{u - u ^{- 1}}{2} \cdot \frac{u + u ^{- 1}}{2} : u = - 1, u = 1

(\frac{u - u ^{- 1}}{2})^{2} = 2 \cdot \frac{u - u ^{- 1}}{2} \cdot \frac{u + u ^{- 1}}{2}

Refine

\frac{( u ^{2} - 1 ) ^{2}}{4 u ^{2}} = \frac{( u ^{2} - 1 ) ( u ^{2} + 1 )}{2 u ^{2}}

Cross multiply

\frac{( u ^{2} - 1 ) ^{2}}{4 u ^{2}} = \frac{( u ^{2} - 1 ) ( u ^{2} + 1 )}{2 u ^{2}}

Apply fraction cross multiply: if

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

then

a \cdot d = b \cdot c

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

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

Solve

(u^{2} - 1)^{2} \cdot 2 u^{2} = 4 u^{2} (u^{2} - 1) (u^{2} + 1) : u = 0, u = - 1, u = 1

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

Move

4 u^{2} (u^{2} - 1) (u^{2} + 1)

to the left side

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

Subtract

4 u^{2} (u^{2} - 1) (u^{2} + 1)

from both sides

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

Simplify

(u^{2} - 1)^{2} \cdot 2 u^{2} - 4 u^{2} (u^{2} - 1) (u^{2} + 1) = 0

(u^{2} - 1)^{2} \cdot 2 u^{2} - 4 u^{2} (u^{2} - 1) (u^{2} + 1) = 0

Factor

(u^{2} - 1)^{2} \cdot 2 u^{2} - 4 u^{2} (u^{2} - 1) (u^{2} + 1) : - 2 u^{2} (u + 1) (u - 1) (u^{2} + 3)

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

Factor

(u^{2} - 1)^{2} : (u + 1)^{2} (u - 1)^{2}

Factor

u^{2} - 1 : (u + 1) (u - 1)

u^{2} - 1

Rewrite

1

1^{2}

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

Apply Difference of Two Squares Formula:

x^{2} - y^{2} = (x + y) (x - y)

u^{2} - 1^{2} = (u + 1) (u - 1)

= (u + 1) (u - 1)

= ((u + 1) (u - 1))^{2}

Apply exponent rule:

(ab)^{n} = a^{n} b^{n}

= (u + 1)^{2} (u - 1)^{2}

Factor

u^{2} - 1 : (u + 1) (u - 1)

u^{2} - 1

Rewrite

1

1^{2}

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

Apply Difference of Two Squares Formula:

x^{2} - y^{2} = (x + y) (x - y)

u^{2} - 1^{2} = (u + 1) (u - 1)

= (u + 1) (u - 1)

= 2 u^{2} (u + 1)^{2} (u - 1)^{2} - 4 u^{2} (u + 1) (u - 1) (u^{2} + 1)

Factor out common term

2 u^{2} (u + 1) (u - 1)

= 2 u^{2} (u + 1) (u - 1) ((u + 1) (u - 1) - 2 (u^{2} + 1))

Expand

(u + 1) (u - 1) - 2 (u^{2} + 1) : - u^{2} - 3

(u + 1) (u - 1) - 2 (u^{2} + 1)

Expand

(u + 1) (u - 1) : u^{2} - 1

(u + 1) (u - 1)

Apply Difference of Two Squares Formula:

(a + b) (a - b) = a^{2} - b^{2}

a = u, b = 1

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

Apply rule

1^{a} = 1

1^{2} = 1

= u^{2} - 1

= u^{2} - 1 - 2 (u^{2} + 1)

Expand

- 2 (u^{2} + 1) : - 2 u^{2} - 2

- 2 (u^{2} + 1)

Apply the distributive law:

a (b + c) = ab + a c

a = - 2, b = u^{2}, c = 1

= - 2 u^{2} + (- 2) \cdot 1

Apply minus-plus rules

+ (- a) = - a

= - 2 u^{2} - 2 \cdot 1

Multiply the numbers:

2 \cdot 1 = 2

= - 2 u^{2} - 2

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

Simplify

u^{2} - 1 - 2 u^{2} - 2 : - u^{2} - 3

u^{2} - 1 - 2 u^{2} - 2

Group like terms

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

Add similar elements:

u^{2} - 2 u^{2} = - u^{2}

= - u^{2} - 1 - 2

Subtract the numbers:

- 1 - 2 = - 3

= - u^{2} - 3

= - u^{2} - 3

= 2 u^{2} (u + 1) (u - 1) (- u^{2} - 3)

Factor

- u^{2} - 3 : - (u^{2} + 3)

- u^{2} - 3

Factor out common term

- 1

= - (u^{2} + 3)

= - 2 u^{2} (u + 1) (u - 1) (u^{2} + 3)

- 2 u^{2} (u + 1) (u - 1) (u^{2} + 3) = 0

Using the Zero Factor Principle:

ab = 0

then

a = 0

b = 0

u = 0 or u + 1 = 0 or u - 1 = 0 or u^{2} + 3 = 0

Solve

u + 1 = 0 : u = - 1

u + 1 = 0

Move

1

to the right side

u + 1 = 0

Subtract

1

from both sides

u + 1 - 1 = 0 - 1

Simplify

u = - 1

u = - 1

Solve

u - 1 = 0 : u = 1

u - 1 = 0

Move

1

to the right side

u - 1 = 0

Add

1

to both sides

u - 1 + 1 = 0 + 1

Simplify

u = 1

u = 1

Solve

u^{2} + 3 = 0 :

No Solution for

u \in R

u^{2} + 3 = 0

Move

3

to the right side

u^{2} + 3 = 0

Subtract

3

from both sides

u^{2} + 3 - 3 = 0 - 3

Simplify

u^{2} = - 3

u^{2} = - 3

x^{2}

cannot be negative for

x \in R

No Solution for u \in R

The solutions are

u = 0, u = - 1, u = 1

u = 0, u = - 1, u = 1

Verify Solutions

Find undefined (singularity) points:

u = 0

Take the denominator(s) of

(\frac{u - u ^{- 1}}{2})^{2}

and compare to zero

u = 0

Take the denominator(s) of

2 \frac{u - u ^{- 1}}{2} \frac{u + u ^{- 1}}{2}

and compare to zero

u = 0

The following points are undefined

u = 0

Since the equation is undefined for:

0

u = - 1, u = 1

u = - 1, u = 1

Substitute back

u = e^{x},

solve for

x

Solve

e^{x} = - 1 :

No Solution for

x \in R

e^{x} = - 1

a^{f (x)}

cannot be zero or negative for

x \in R

No Solution for x \in R

Solve

e^{x} = 1 : x = 0

e^{x} = 1

Apply exponent rules

e^{x} = 1

f (x) = g (x)

, then

ln (f (x)) = ln (g (x))

ln (e^{x}) = ln (1)

Apply log rule:

ln (e^{a}) = a

ln (e^{x}) = x

x = ln (1)

Simplify

ln (1) : 0

ln (1)

Apply log rule:

lo g_{a} (1) = 0

= 0

x = 0

x = 0

x = 0

x = 0

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Frequently Asked Questions (FAQ)

What is the general solution for sinh^2(x)=2sinh(x)cosh(x) ?
The general solution for sinh^2(x)=2sinh(x)cosh(x) is x=0