Câu hỏi 30Nếu $\sin x+\cos x=m$, tính $\sin^4x+\cos^4x$.$1-\frac{(1-m^2)^2}{2}$$1+\frac{(1-m^2)^2}{2}$$\frac{1-(1-m^2)^2}{2}$$m^4$$m^4+1$