b^4 - 9 = 10(b^2-1) <=> (b^2)^2 - 10b^2 + 1 = 0 <=> b^2 = 5 + sqrt(5^2 - 1) \/ b^2 = 5 - sqrt(5^2 - 1) /**/ <=> b^2 = 5 + sqrt(24) \/ b^2 = 5 - sqrt(24) /**/ <=> b = sqrt( 5 + sqrt(6*4) ) \/ b = sqrt( 5 - sqrt(6*4) ) \/ b = -sqrt( 5 + sqrt(6*4) ) \/ b = -sqrt( 5 - sqrt(6*4) ) /**/ <=> b = sqrt( 2 + 2sqrt(2)sqrt(3) + 3 ) \/ b = sqrt( 2 - 2sqrt(2)sqrt(3) + 3 ) \/ b = -sqrt( 2 + 2sqrt(2)sqrt(3) + 3 ) \/ b = -sqrt( 2 - 2sqrt(2)sqrt(3) + 3 ) /**/ <=> b = sqrt(2) + sqrt(3) \/ b = sqrt(2) - sqrt(3) \/ b = sqrt(3) - sqrt(2) \/ b = -sqrt(2) - sqrt(3)