a -h 6)^ = a^ -+- 4a3& H- 6aV -+- 4afe

43. » =^ 2(a« -+- &* -4- c^) (a -f- & -K c)* -H- Sa&c(a -h b-h c)

H- 2(a«62 ^. «2^2 ^ ^,2^^) (^ ^^ fti ^ c*)

44. a(&--c)3H-5(c— af-+-<a---&)3==(a— &)(&— c)(c---a)(a-+-6-hc) .

45. a^{b—c) H- &^(c— a) -+- c^(a— &i = (a—b) (a-rc) (6— c) .(aH-&-4-c) .

46. (aH-&H-ç)(a-h& — c)(a~6-^-c)(-.ra-h5-^-c)=2(a2&2-^-aV4-•&V)-- 47. (a»-H62)(a'2H-&'2) (^':^^jy^(^5'^'^)2(^^'^^')2^(^'^^'2,)^ .,

49. (a« -+- c62) (a'2 -f- cb'^ = {aa' -h- cbb'Y -h c(ab' — à'&)« .