Question

x^2+9x,x^2+18x+81,x^2-81的公因式

Answer 1

x^2+9x=x(x+9),

x^2+18x+81=(x+9)^2,

x^2-81=(x+9)(x-9).

所以,x^2+9x,x^2+18x+81,x^2-81的公因式为x+9