Расчет: nx52ad - 1

DX  = 
 (x1-EX)^2* p1+ (x2-EX)^2* p2+ (x3-EX)^2* p3
DX =  (x1-EX)^2* p1+ (x2-EX)^2* p2+ (x3-EX)^2* p3$$DX$$ = $$(x1-EX)^{2}\cdot p1+(x2-EX)^{2}\cdot p2+(x3-EX)^{2}\cdot p3$$
DX =  x1^2* p1- 2* x1* EX* p1+ EX^2* p1+ x2^2* p2- 2* x2* EX* p2+ EX^2* p2+ x3^2* p3- 2* x3* EX* p3+ EX^2* p3$$DX$$ = $$x1^{2}\cdot p1-2\cdot x1\cdot EX\cdot p1+EX^{2}\cdot p1+x2^{2}\cdot p2-2\cdot x2\cdot EX\cdot p2+EX^{2}\cdot p2+x3^{2}\cdot p3-2\cdot x3\cdot EX\cdot p3+EX^{2}\cdot p3$$
DX =  p1* x1^2- 2* EX* p1* x1+ EX^2* p1+ p2* x2^2- 2* EX* p2* x2+ EX^2* p2+ p3* x3^2- 2* EX* p3* x3+ EX^2* p3$$DX$$ = $$p1\cdot x1^{2}-2\cdot EX\cdot p1\cdot x1+EX^{2}\cdot p1+p2\cdot x2^{2}-2\cdot EX\cdot p2\cdot x2+EX^{2}\cdot p2+p3\cdot x3^{2}-2\cdot EX\cdot p3\cdot x3+EX^{2}\cdot p3$$