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Consider biquadratic equation 81x^(4) + ...

Consider biquadratic equation `81x^(4) + 216x^(3) +96x = 65`, whose roots are `a,b,c,d`. Given `a,b`, real roots and c,d are imaginary roots.
On the basis of above information, answer the followin questions:
The value of `(a+b)^(3) - (c+d)^(3)` is equal to-

A

`(-128)/(3)`

B

0

C

`(-64)/(3)`

D

`(-142)/(9)`

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To solve the biquadratic equation \( 81x^4 + 216x^3 + 96x = 65 \) and find the value of \( (a+b)^3 - (c+d)^3 \), where \( a, b \) are real roots and \( c, d \) are imaginary roots, we will follow these steps: ### Step 1: Rearrange the Equation First, we rearrange the equation to set it to zero: \[ 81x^4 + 216x^3 + 96x - 65 = 0 \] ### Step 2: Factor the Equation We can factor the left-hand side. Notice that we can rewrite the equation: \[ 81x^4 + 216x^3 + 96x = 65 \] This can be factored as: \[ (3x + 2)^4 - 9^2 = 0 \] This is in the form of \( a^2 - b^2 = 0 \), which can be factored as: \[ (3x + 2)^2 - 9 = 0 \] ### Step 3: Solve for Real Roots Now, we solve the two equations: 1. \( (3x + 2)^2 - 9 = 0 \) 2. \( (3x + 2)^2 + 9 = 0 \) From the first equation: \[ (3x + 2)^2 = 9 \] Taking the square root gives: \[ 3x + 2 = 3 \quad \text{or} \quad 3x + 2 = -3 \] Solving these: 1. \( 3x + 2 = 3 \) leads to \( 3x = 1 \) or \( x = \frac{1}{3} \) 2. \( 3x + 2 = -3 \) leads to \( 3x = -5 \) or \( x = -\frac{5}{3} \) Thus, the real roots are \( a = \frac{1}{3} \) and \( b = -\frac{5}{3} \). ### Step 4: Solve for Imaginary Roots From the second equation: \[ (3x + 2)^2 + 9 = 0 \] This gives: \[ (3x + 2)^2 = -9 \] Taking the square root gives: \[ 3x + 2 = 3i \quad \text{or} \quad 3x + 2 = -3i \] Solving these: 1. \( 3x + 2 = 3i \) leads to \( 3x = 3i - 2 \) or \( x = -\frac{2}{3} + i \) 2. \( 3x + 2 = -3i \) leads to \( 3x = -3i - 2 \) or \( x = -\frac{2}{3} - i \) Thus, the imaginary roots are \( c = -\frac{2}{3} + i \) and \( d = -\frac{2}{3} - i \). ### Step 5: Calculate \( a + b \) and \( c + d \) Now, we calculate: \[ a + b = \frac{1}{3} - \frac{5}{3} = -\frac{4}{3} \] \[ c + d = \left(-\frac{2}{3} + i\right) + \left(-\frac{2}{3} - i\right) = -\frac{4}{3} \] ### Step 6: Calculate \( (a+b)^3 - (c+d)^3 \) Now we substitute into the expression: \[ (a+b)^3 - (c+d)^3 = \left(-\frac{4}{3}\right)^3 - \left(-\frac{4}{3}\right)^3 \] Since both terms are equal, we have: \[ (a+b)^3 - (c+d)^3 = 0 \] ### Final Answer Thus, the value of \( (a+b)^3 - (c+d)^3 \) is: \[ \boxed{0} \]

To solve the biquadratic equation \( 81x^4 + 216x^3 + 96x = 65 \) and find the value of \( (a+b)^3 - (c+d)^3 \), where \( a, b \) are real roots and \( c, d \) are imaginary roots, we will follow these steps: ### Step 1: Rearrange the Equation First, we rearrange the equation to set it to zero: \[ 81x^4 + 216x^3 + 96x - 65 = 0 \] ...
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