EXAMPLES OF MAXIMA AND MINIMA. 



Multiply (6) by X, and (7) by fi, and add to (5) ; tnen 

 equate to zero the coefficients of Dx, Dy, and Dz ; thus, 



x ct + 



Cb 



n dti\ 



c 2 



Multiply (8), (9), and (10) by x-a, y-@, and z - 

 respectively, and add ; thus by (2) and (3) 



, 



by (2) and (3) 



. y (y - ft) t 



"~ 



that is, 



Now by (4) 



VV V \J HV \S IV tV V I \S '* I V * 



thus (11) becomes with the help of (2) 

 r 2 = 



P 



Thus (8), (9), and (10) may be written 



.(12). 



By substituting the values of x, y, and z from these in (2), 

 we obtain 



Ike? (a. fj,T) mkb* (J3 fim) nfec 3 (7 /in) _ 

 ' 2 ~ 



also 



