25. If (a + b) = 8 and ab =12, find the value of a3 – b3.
[Hint: (a – b)2 = (a + b)2 – 4ab]
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1 thought on “25. If (a + b) = 8 and ab =12, find the value of a3 – b3.<br />[Hint: (a – b)2 = (a + b)2 – 4ab]<br />​”

1. Answer:

   Step-by-step explanation:

   a + b = 8 |given|

   ab = 12

   •°• we know that

   a³ + b ³ = (a + b ) ( a² + b² – ab )

   and , ( a + b ) ²- 2ab = a² + b²

   so , a³ + b³= ( a + b ){ ( a + b )² – 3ab }

   hence , a³ + b³ = 8{8²- 3 ×12 } ✔ putting the given value

   => 8 { 64- 36}

   => 8×28

   = > 224 Answer

   a³ + b³ = 224 Answer

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