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If x = (3)/(2) rthen the value of 27 x ...

If `x = (3)/(2) ` rthen the value of `27 x ^(3) - 54 x ^(2) + 36 x - 11 `is

A

`11 (3)/(8)`

B

`11 (5)/(8)`

C

`12 (3)/(8)`

D

`12 (5)/(8)`

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The correct Answer is:
To find the value of the expression \( 27x^3 - 54x^2 + 36x - 11 \) when \( x = \frac{3}{2} \), we will substitute \( x \) into the expression and simplify step by step. ### Step 1: Substitute \( x \) into the expression We start with the expression: \[ 27x^3 - 54x^2 + 36x - 11 \] Substituting \( x = \frac{3}{2} \): \[ 27\left(\frac{3}{2}\right)^3 - 54\left(\frac{3}{2}\right)^2 + 36\left(\frac{3}{2}\right) - 11 \] ### Step 2: Calculate \( x^3 \) and \( x^2 \) Calculate \( \left(\frac{3}{2}\right)^3 \) and \( \left(\frac{3}{2}\right)^2 \): \[ \left(\frac{3}{2}\right)^2 = \frac{9}{4} \] \[ \left(\frac{3}{2}\right)^3 = \frac{27}{8} \] ### Step 3: Substitute back into the expression Now substitute these values back into the expression: \[ 27\left(\frac{27}{8}\right) - 54\left(\frac{9}{4}\right) + 36\left(\frac{3}{2}\right) - 11 \] ### Step 4: Simplify each term Now we simplify each term: 1. \( 27 \times \frac{27}{8} = \frac{729}{8} \) 2. \( 54 \times \frac{9}{4} = \frac{486}{4} = \frac{972}{8} \) 3. \( 36 \times \frac{3}{2} = 54 \) Now, convert \( 54 \) to have a denominator of 8: \[ 54 = \frac{432}{8} \] ### Step 5: Combine all terms Now we can combine all the terms: \[ \frac{729}{8} - \frac{972}{8} + \frac{432}{8} - \frac{88}{8} \] Combine the numerators: \[ 729 - 972 + 432 - 88 = 729 - 972 = -243 \] \[ -243 + 432 = 189 \] \[ 189 - 88 = 101 \] ### Step 6: Write the final result Now we have: \[ \frac{101}{8} \] ### Conclusion Thus, the value of \( 27x^3 - 54x^2 + 36x - 11 \) when \( x = \frac{3}{2} \) is: \[ \frac{101}{8} \]
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