One morning Mr. Green is driving 1the country and2a small bookshop. When he sees an old man3the side of the road, he stops his car and says to the old man, "I want 4to the Sun Bookshop. Do you know it?" "Yes, "the old man answers, "I 5 you the way. "He6Mr. Green's car, and they drive about twelve miles.7they come to a small house, the old man says, "Stop here. "Mr. Green stops and 8the house. "But this isn't a bookshop, "he says to the old man. "Right, "the old man answers, "This is my house. And I'll show you the way 9the bookshop. Turn around and go back nine miles10you'll see the bookshop. "

如图所示，在光滑的水平面上叠放着M，P，N三个物体，质量分别为m，2m和m，M，N，P间动摩擦因数均为μ，系统处于静止状态，现对P施加一个水平向右的拉力F，欲使P从M和N中拉出来，则F必须大于（   ）

设a，b是方程x²+x-2009=0的两个实数根，则a²+2a+b的值为（　　）