How to find the value of (a-b)² + (b-c)² + (c-a)² When a + b + c = 6 and a² + b² + c² = 14?
Problem Statement:
If a + b + c = 6 and a² + b² + c² = 14, find the value of (a-b)² + (b-c)² + (c-a)².
Solution:
The formula for (a-b)² + (b-c)² + (c-a)² is:
(a-b)² + (b-c)² + (c-a)² = 2(a² + b² + c²) - 2(ab + bc + ca).
From the problem:
a + b + c = 6 → (a + b + c)² = 36.
Expand (a + b + c)²:
a² + b² + c² + 2(ab + bc + ca) = 36.
Substitute a² + b² + c² = 14:
14 + 2(ab + bc + ca) = 36.
2(ab + bc + ca) = 22 → ab + bc + ca = 11.
Now substitute values into the formula:
(a-b)² + (b-c)² + (c-a)² = 2(a² + b² + c²) - 2(ab + bc + ca).
= 2(14) - 2(11) = 28 - 22 = 6.
Final Answer:
The value is 6.
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