∫(－∞,＋∞）f(x)dt
=∫[1,2]Ax^2dx+∫[2,3]Axdx
=A/3*x^3[1,2]+A/2x^2[2,3]
=7/3A+5/2A
=1
A=6/29
F(x)=∫(－∞,x）f(t)dt
=0 (x