Solved on Feb 10, 2024

Find the value of cosh(3ln3)sinh(3ln3)\cosh(3\ln 3) - \sinh(3\ln 3).

STEP 1

Assumptions
1. We are given the hyperbolic functions cosh(3x)\cosh(3x) and sinh(3x)\sinh(3x).
2. We need to evaluate these functions at x=ln3x = \ln 3.
3. The hyperbolic cosine and hyperbolic sine functions are defined as: coshx=ex+ex2\cosh x = \frac{e^x + e^{-x}}{2} sinhx=exex2\sinh x = \frac{e^x - e^{-x}}{2}
4. We will use properties of logarithms and exponentials to simplify the expressions.

STEP 2

First, we will write the expression cosh(3x)sinh(3x)\cosh(3x) - \sinh(3x) using the definitions of coshx\cosh x and sinhx\sinh x.
cosh(3x)sinh(3x)=e3x+e3x2e3xe3x2\cosh(3x) - \sinh(3x) = \frac{e^{3x} + e^{-3x}}{2} - \frac{e^{3x} - e^{-3x}}{2}

STEP 3

Now, we simplify the right-hand side by combining the fractions.
cosh(3x)sinh(3x)=e3x+e3xe3x+e3x2\cosh(3x) - \sinh(3x) = \frac{e^{3x} + e^{-3x} - e^{3x} + e^{-3x}}{2}

STEP 4

Next, we cancel out the e3xe^{3x} terms.
cosh(3x)sinh(3x)=2e3x2\cosh(3x) - \sinh(3x) = \frac{2e^{-3x}}{2}

STEP 5

Simplify the expression by dividing both the numerator and the denominator by 2.
cosh(3x)sinh(3x)=e3x\cosh(3x) - \sinh(3x) = e^{-3x}

STEP 6

Now we need to evaluate the expression at x=ln3x = \ln 3. Substitute xx with ln3\ln 3.
cosh(3ln3)sinh(3ln3)=e3ln3\cosh(3\ln 3) - \sinh(3\ln 3) = e^{-3\ln 3}

STEP 7

Recall the property of logarithms that states elna=ae^{\ln a} = a. We will use this to simplify the exponent.
e3ln3=(eln3)3e^{-3\ln 3} = (e^{\ln 3})^{-3}

STEP 8

Apply the property of logarithms to simplify further.
(eln3)3=33(e^{\ln 3})^{-3} = 3^{-3}

STEP 9

Calculate the value of 333^{-3}.
33=1333^{-3} = \frac{1}{3^3}

STEP 10

Calculate the value of 333^3.
33=3×3×3=273^3 = 3 \times 3 \times 3 = 27

STEP 11

Now, divide 1 by 27 to get the final value.
33=1273^{-3} = \frac{1}{27}
The value of cosh(3x)sinh(3x)\cosh(3x) - \sinh(3x) at x=ln3x = \ln 3 is 127\frac{1}{27}.

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