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Please refer to attachment below — having a hard time answering this one. |
Answer» Answer:-Given: a + b + c = 5 -- equation (1) ab + bc + CA = 10 -- equation (2) We KNOW that, a³ + b³ + c³ - 3ABC = (a² + b² + c² - ab - bc - ca)(a + b + c) => (5)[a² + b² + c² -(ab + bc + ca)] Again , a² + b² + c² = (a + b + c)² - 2(ab + bc + ca) Substitute the values, => a² + b² + c² = (5)² - 2(10) = 25 - 10 => a² + b² + c² = 5 => a³ + b³ + c³ - 3abc = 5(5 - 10) => a³ + b³ + c³ - 3abc = - 25 Hence, proved. |
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