If 2x + 3y + 1 = 0 , then what is the value of (8x3 + 8 + 27y3 - 18xy)?
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 7
2x + 3y + 1 = 0
2x + 3y = -1
On cubing both sides we get,
(8x3 + 27y3 + 12xy(2x + 3y)) = -1
(8x3 + 27y3 - 18xy) = -1
(8x3 + 27y3 - 18xy + 8) = 8 - 1
(8x3 + 27y3 - 18xy + 8) = 7.