If a3 + b3 = 217 and a + b = 7, then the value of ab is:
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Correct answer: D
Explanation
The correct answer is Option 4 i.e. 6.
Given:
a3 + b3 = 217
(a + b) = 7
Formula Used:
⇒ (a + b)3 = a3 + b3 + 3ab (a + b)
Calculation:
Substituting the values in the formula
⇒ (7)3 = 217 + 3ab (7)
⇒ 343 - 217 = 21ab
⇒ 126/21 = ab
Thus, the value of ab is = 6