m= ∫ ∫ _( Δ ABC) x^2dxdy
D= Δ ABC
0 ≤ y ≤ 4
y/2≤ x ≤6-y
m= ∫_(0)^(4) (∫_(y/2)^(6-y)x^2dx)dy=
=∫_(0)^(4) (x^3/3)|_(y/2)^(6-y)dy=
=(1/3)∫_(0)^(4) ((6-y)^3-(y/2)^3)dy=
=(1/3)∫_(0)^(4) (216-108y+18y^2-y^3-(y^3/8))dy=
=(1/3)∫_(0)^(4) (216-108y+18y^2-(9y^3/8))dy=
=(1/3)*(216y-(108y^2/2)+18*(y^3/3)-(9/8)*(y^4/4))|^(4)_(0)=
=(1/3)*(216*4-54*16+6*64-72)=...