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If a + b + c = 11 and ab + bc + ca = 15, then what is the value of $a^3 + b^3 + c^3 -3abc $ ? |
368 836 386 638 |
836 |
Given, a + b + c = 11 ab + bc + ca = 15 We know that, a3 + b3 + c3 – 3abc = (a + b + c)[(a + b + c)2 – 3(ab + bc + ca)] Calculation: a3 + b3 + c3 - 3abc = [11{(11)2 - 3 × 15}] = [11{121 – 3 × 15] = [11{121 – 45}] = 11 × 76 = 836 |
