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CUET
General Test
Quantitative Reasoning
Algebra
If a - b = 2 and a3 − b3 = 80, then what will be the value of ab?
12
-24
24
-12
a3 - b3 = (a - b)3 + 3ab(a - b)
a3 - b3 = 80
= (a - b)3 + 3ab(a - b) = 80
= 23 + 3ab × 2 = 80
= ab = 12
