If a=cos left( frac{2pi }{7} ight)+i,sin left( frac{2pi }{7} ight), then the quadratic equation whose roots are a = a + a2 + a4 and b = a3 + a5 + a6 is
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If a=cos left( frac{2pi }{7} ight)+i,sin left( frac{2pi }{7} ight), then the quadratic equation whose roots are a = a + a2 + a4 and b = a3 + a5 + a6 is