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If (x-y)=4 and xy = 45, then the value o...

If `(x-y)=4` and `xy = 45`, then the value of `x^(3) - y^(3)` is:

A

82

B

604

C

822

D

151

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to find the value of \( x^3 - y^3 \) given that \( x - y = 4 \) and \( xy = 45 \). ### Step-by-step Solution: 1. **Use the identity for the difference of cubes**: The formula for the difference of cubes is: \[ x^3 - y^3 = (x - y)(x^2 + xy + y^2) \] We already know \( x - y = 4 \). 2. **Calculate \( x^2 + xy + y^2 \)**: We need to find \( x^2 + xy + y^2 \). We can express \( x^2 + y^2 \) in terms of \( (x - y)^2 \) and \( xy \): \[ x^2 + y^2 = (x - y)^2 + 2xy \] Substituting the known values: \[ x^2 + y^2 = (4)^2 + 2 \cdot 45 = 16 + 90 = 106 \] Now, we can find \( x^2 + xy + y^2 \): \[ x^2 + xy + y^2 = x^2 + y^2 + xy = 106 + 45 = 151 \] 3. **Substitute back into the difference of cubes formula**: Now we can substitute back into the formula for \( x^3 - y^3 \): \[ x^3 - y^3 = (x - y)(x^2 + xy + y^2) = 4 \cdot 151 = 604 \] 4. **Final Answer**: Therefore, the value of \( x^3 - y^3 \) is \( 604 \). ### Conclusion: The correct option is \( 604 \).
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