Definition: A function u(x , y) is an integrating factor for the differential equation

M(x ,y)+N(x ,y)=0, if the equation obtained by multiplying by u(x , y)

u(x , y) M(x ,y)+u(x , y)N(x , y)=0, is exact.

If (M_y – N_x )/N=Q(x) is a function of x only, then

Assignment:  sec 1.14, problems 1, 3, 5