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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