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Question
a2 + b2 + c2 = 66, ab − bc − ca = 17 ∴ a + b − c = ______.
Options
12
11
9
10
MCQ
Fill in the Blanks
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Solution
a2 + b2 + c2 = 66, ab − bc − ca = 17 ∴ a + b − c = 10.
Explanation:
(a + b − c)2 = a2 + b2 + c2 + 2(ab − bc − ca)
(a + b − c)2 = 66 + 2(17)
(a + b − c)2 = 66 + 34
(a + b − c)2 = 100
a + b − c = `sqrt100`
a + b − c = 10
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