aîH-2/==a.a? — ^ = &. = .aî = (a-+- &)/2 .y = {a

7. i?, g,Jp-f-g-=0.o:aî-h2/=a.aî/p=2//â'•=•^"=i^«/(i'^-5')•y=â'«/(p-^-?^ •

8. y-4-2; = a.0-i-aî = 6.aî-hy ==c. = .a? = (&h- c — a)/2 . y = (a-f-

9. y-hz—x^a . z-\-x—'y = b .x-k-y — z^c .=. a? = (6 h- c)/2 . y = ...

10. 06'— al)~ = O.o:ax-^by = c.a'x -4- è'^ = c'.==.aî = {cb'—c'b)l{ab'—a'b).

y = (ac'—a'c)l(àb'—a'b) .

11. x^ysq.- {x=0.y=0).ax-\-by=0.a'x-hb'y=0.'- =^, ^a :=: oô'— a'&=0.

12. (a—jb) (a— c) (&— c)- = . i a? -h y -+- ^==1 . aaîH-62/-f-C0= d\a^x-\-b^y-+-

13. a6c-=0.o:a?2/ = a .2/^==6%2;a?=c\='.ii?=— -- . î/ = -; — . z =

+ b ih<^ . it^

2 — Formuf.

.aî* = a*.==.a; = a.^.a;== — a.