a) (8m^2+5m)+(1-6m)
8m^2+5m+1-6m
= 8m^2-m+1
b) (x^2+5xy-y^2)-(6xy+9y^2-8x^2)
x^2+5xy-y^2-6xy-9y^2+8x^2
9x^2-xy-10y^2
9x^2+9xy-10xy-10y^2
9x*(x+y)-10y*(x+y)
= (x+y)*(9x-10y)
a) (8m^2+5m)+(1-6m)
8m^2+5m+1-6m
= 8m^2-m+1
b) (x^2+5xy-y^2)-(6xy+9y^2-8x^2)
x^2+5xy-y^2-6xy-9y^2+8x^2
9x^2-xy-10y^2
9x^2+9xy-10xy-10y^2
9x*(x+y)-10y*(x+y)
= (x+y)*(9x-10y)