If a3 = b3 + 988 and a - b = 4, then what is the value of 2a2 + 2ab + 2b2 ?
Answer & explanation
Correct answer: option 2
If a3 = b3 + 988
a - b = 4
According to the question,
a3 - b3 = 988
a3 - b3 = ( a - b ) ( a2 + b2 + ab )
988 = 4 ( a2 + b2 + ab )
( a2 + b2 + ab ) = 247
2a2 + 2ab + 2b2 = 2 × 247 = 494