[질문] (x+y+z)^7전개식이 뭐예요?

(x+y+z)^7 = 128*x^7+448*y*x^6+672*y^2*x^5+560*y^3*x^4+280*y^4*x^3+84*y^5*x^2+14*y^6*x+y^7