A THIRD MEMOIR UPON QUANTICS.
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144
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48
±222 ±222 ±222 ±408 ±408 ±408 ±408 ±408 ±408 ±558
The preceding Tables contain the complete system [not so] of the covariants and
contravariants of the ternary cubic, i.e. the covariants are the cubic itself U, the
quartinvariant 8, the sextinvariant T, the Hessian HU, and an octicovariant, say ( H ) U;
the contravariants are the cubicontra variant PU, the quinticontravariant QU, and
the reciprocant FU.
The contravariants are all of them evectants, viz. PU is the evectant of 8, QU
is the evectant of T, and the reciprocant FU is the evectant of QU, or what is the
same thing, the second evectant of T.
The discriminant is a rational and integral function of the two invariants; repre
senting it by FI, we have R = 64 8 Z — T\
If we combine U and HU by arbitrary multipliers, say a and 6/3, so as 1° form
the sum aU+6/3HU, this is a cubic, and the question arises, to find the covariants
and contravariants of this cubic : the results are given in the following Table:
No. 68.
aU + 6/3HU = aU+6/3IIU.
H (a U + 6/3HU) = (0, 28, T, 8& $ a, /3) 3 U
+ (1, 0, - 12$, - 2T\a, /3fHU
C. II.
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