Question

Помогите с номером 31.7 (2 столбик) пжпжпжп

Answer 1

Лови)

c2+(9-c)(9+c)=c2+81-c2=81

-16/49+(4/7-d)(d+4/7)= -16/49+ (4/7-d)(4/7+d)= -16/49 + 16/49-d2=d2

k(5-k)+(1,2+k)(k-1,2)=5k-k2+ (k+1,2)(k-1,2)=5k-k2+k2-1,44=5k-1,44