1) a²+4²-9c²-4ab

x³+x²-xy²-y²

2) (5+2x) ²-2.5x (8x+7) при x=-0.5

X^3+x^2-xy^2-y^2 = (x^3+x^2) - (xy^2+y^2) = x^2 (x+1) - y^2 (x+1) = (x^2-y^2) (x+1)

2) 5+2 * (-0,5) - 2,5 * (-0,5) * (8 * (-0,5) + 7) = 5-1+1,25*3=4-3,75=7,75

= (a^2-9c^2) - (4^2+4ab) = (a-3c) (a+3c) - 4 (1+ab)