``
1. 作下列函数的大致图形, 要求反映出函数的增减性及极值点、凸凹性及拐点、周期性 (如有)、奇偶性 (如有) 和渐近线 (如有) 等特性:
   1. `y = 3x - x^3`;
   2. `y = 1 + x^2 - 1/2 x^4`;
   3. `y = sin x + 1/3 sin 3x`;
   4. `y = sin^4 x + cos^4 x`;
   5. `y = (1+x^2) e^(-x^2)`;
   6. `y = ln(x + sqrt(x^2+1))`;
   7. `y = arcsin {:(2x)/(1+x^2):}`;
   8. `y = x arctan x`;
   9. `y = arcsin {:(x-3)^2/(4(x-1)):}`;
   10. `y = sqrt(x^3/(x-2))`.