If a-b=4 and ab=21 find the value of a3-b3
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GIVEN: a - b = 4
ab = 21 find the value of a³-b³
Putting the value in the formula>
(a-b)³ = a³ - b³ - 3ab(a-b)
(4)³ = a³ - b³ - 3(21)(4)
64 = a³ - b³ - 252
64 + 252 = a³ - b³
316 = a³ - b³
Hence, a³ - b³ = 316
ab = 21 find the value of a³-b³
Putting the value in the formula>
(a-b)³ = a³ - b³ - 3ab(a-b)
(4)³ = a³ - b³ - 3(21)(4)
64 = a³ - b³ - 252
64 + 252 = a³ - b³
316 = a³ - b³
Hence, a³ - b³ = 316
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