If x² + y² = 221 and x - y = I then the value of x³ - y³ is
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Answer:
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Step-by-step explanation:
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Answer:
The value of x³ - y³ is 331.
Step-by-step-explanation:
We have given that,
x² + y² = 221 - - - ( 1 ) &
x - y = 1 - - - ( 2 )
We have to find the value of x³ - y³.
Now,
x - y = 1 - - - ( 2 )
⇒ x = 1 + y
⇒ x = y + 1 - - - ( 3 )
By substituting this value in equation ( 1 ), we get,
x² + y² = 221 - - - ( 1 )
⇒ ( y + 1 )² + y² = 221
⇒ y² + 2y + 1 + y² = 221
⇒ y² + y² + 2y + 1 - 221 = 0
⇒ 2y² + 2y - 220 = 0
⇒ y² + y - 110 = 0
⇒ y² + 11y - 10y - 110 = 0
⇒ y ( y + 11 ) - 10 ( y + 11 ) = 0
⇒ ( y + 11 ) ( y - 10 ) = 0
⇒ ( y + 11 ) = 0 OR ( y - 10 ) = 0
⇒ y + 11 = 0 OR y - 10 = 0
⇒ y = - 11 OR y = 10
Now, by substituting y = - 11 in equation ( 3 ), we get,
x = y + 1 - - - ( 3 )
⇒ x = - 11 + 1
⇒ x = - 10
Now,
x³ - y³ = ( - 10 )³ - ( - 11 )³
⇒ x³ - y³ = - 1000 - ( - 1331 )
⇒ x³ - y³ = - 1000 + 1331
⇒ x³ - y³ = 331
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Now, by substituting y = 10 in equation ( 3 ), we get,
x = y + 1 - - - ( 3 )
⇒ x = 10 + 1
⇒ x = 11
Now,
x³ - y³ = ( 11 )³ - ( 10 )³
⇒ x³ - y³ = 1331 - 1000
⇒ x³ - y³ = 331
∴ The value of x³ - y³ is 331.