a)$5y^3-15y^2=5y^2(y-3)$
b)$10y^3-15y^2=5y^2(2y-3)$
c)$6x^3-14x^2=2x^2(3x-7)$
d)$3x^3+9x^2=3x^2(x+3)$
e)$8x^3+12x^2=4x^2(2x+3)$
f)$x^2-2xy-1+y^2=(x-y)^2-1=(x-y-1)(x-y+1)$
g) $x^2-6xy-1+9y^2=x^2-2x3y+(3y)^2-1=(x-3y)^2-1=(x-3y-1)(x-3y+1)$
h) $x^2-6x-y^2+9=x^2-2x3+3^2-y^2=(x-3)^2-y^2=(x-3-y)(x-3+y)$