trigonometry

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1)Solve and write in standard form:
4x^2-4x+21=0



2)Find the standard form of the complex number.
8(cos pi/2 + i sin pi/2)

Thanks everyone!

  • trigonometry -

    x = (4 ± √(16 - 16(21)) )/8
    = (4 ± √-320)/8
    = (4 ± 8√-5)/8
    = 1/2 ± i√5

    x = 1/2 + i√5 or x = 1/2 - i√5

    2)
    8(cos π/2 + i sin π/2)
    = 8(√2/2 + i √2/2)
    = 4√2 + i (4√2)

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