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If A = [αβγ-α] is such that A2 = I then ______. - Mathematics

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प्रश्न

If A = `[(alpha, beta),(gamma, -alpha)]` is such that A2 = I then ______.

विकल्प

  • 1 + α² + βγ = 0

  • 1 – α² + βγ = 0

  • 1 – α² – βγ = 0

  • 1 + α² – βγ = 0

MCQ
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उत्तर

If A = `[(alpha, beta),(gamma, -alpha)]` is such that A2 = I then 1 – α² – βγ = 0.

Explanation:

A = `[(alpha, beta), (ϒ, -alpha)]`

`"A"^2 = "A" * "A"[(alpha, beta), (ϒ, -alpha)][(alpha, beta), (ϒ, -alpha)]`

= `[(alpha^2 + betaϒ, alphabeta - alphabeta), (alphaϒ - alphaϒ, betaϒ + alpha^2)] = [(1, 0), (0, 1)]`

Now, A2 = I

⇒ `[(alpha^2 + betaϒ,0), (0, betaϒ + alpha^2)] = [(1, 0), (0, 1)]`

α2 + βγ = 1 or 1 – α2 – βγ = 0

Accordingly, option (1 - α2 - βγ = 0) is correct.

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अध्याय 3: Matrices - Exercise 3.5 [पृष्ठ १०१]

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एनसीईआरटी Mathematics Part 1 and 2 [English] Class 12
अध्याय 3 Matrices
Exercise 3.5 | Q 13 | पृष्ठ १०१

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