Вправа 201 - 300 » 214 (в)

в) ((y- b)(z- b))/(b(b- c)) + ((y- c)(z- c))/(c(c- b)) + yz/bc = 1; ((y- b)(z- b))/(b(b- c)) – ((y- c)(z- c))/(c(b- c)) + yz/bc = 1; (c(yz- yb+ bz+b^2 )- b(yz- yc- cz+c^2 )+ yz(b- c) )/(bc(b- c)) = 1; (cyz- cyb- cbz+ cb^2- byz+ byc+ bcz- bc^2+ yzb- yzc)/(bc(b- c)) = 1; (b^2 c- bc^2)/(b^2 c- bc^2 ) = 1; 1 = 1. Тотожність доведено.