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If a + b - c = -5 and ab - bc - ac = 10, then find the value of $a^2 + b^2 + c^2 $ |
40 5 45 15 |
5 |
a + b - c = 5 ab - bc - ac = 10 (a + b - c)2 = a2 + b2 + c2 + 2ab - 2bc - 2ac = (5)2 = a2 + b2 + c2 + 2(ab - bc - ac) = 25 = a2 + b2 + c2 + 2 × 10 = a2 + b2 + c2 = 25 - 20 = a2 + b2 + c2 = 5 |
