解由y=x^7-x^(3/2)求导得y'=(x^7)'-(x^(3/2))'即y'=7x^6-3/2x^(3/2-1)故y'=7x^6-3/2x^(1/2)
f(x) = x^7 + 7^xf ′(x) = 7x^6 + 7^x * ln7
