原式 = lim [ x^2 - (sinx)^2(cosx)^2 ] / [ x^2 (sinx)^2 ]= lim [ x^2 - 1/4 (sin2x)^2 ] / x^4 【sinx~x】= lim [ x^2 - 1/8(1-cos4x) ] / x^4= lim [ 2x - 1/2 sin4x ] / 4x^3= lim [ 2 - 2cos4x ] / 12x^2= lim...