Question : If $a - b = 2$ and $a^3 - b^3 = 80$, then what will be the value of $ab$?
Option 1: 12
Option 2: –24
Option 3: 24
Option 4: –12
Answer (1)
25th Jan, 2024
Correct Answer: 12
Solution :
Given: $a - b = 2$ and $a^3 - b^3 = 80$
Consider $a - b = 2$
Cubing both sides we get,
$⇒a^3-b^3-3ab(a-b)=8$
$⇒80-3ab(2)=8$
$⇒6ab=72$
$\therefore ab = 12$
Hence, the correct answer is 12.
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