How many of the following equations are partial differential equations?
a) u^{}2_{}x(x, y)+2u_{yy}(x, y)=cos(2x+5y)
b)3u_{}x(x, y)+2u_{yy}(x, y)=0
c)(iii) u_{xx}(x, t)= -u_{tt}(t, x)-u_{t}(t, x)
d)3u_{xx}(x, y)+2u_{yy}(y, x)=3u_{}x(x, y)
e)u_{xx}(x, y)+3u_{yy}(x+\pi ,y)=-u_{}x(x, y)+u_{}y(x, y-\pi )
f)ey^{}2u_{}x(x, y)+x^{}4u_{}y(x, y)=tan(x)
g)u^{}2_{}x(x, y)+2u_{yy}(x, y)=cos(2x+5y)

Asays "we are both knaves" and b says nothing. exercises 24–31 relate to inhabitants of an island on which there are three kinds of people: knights who always tell the truth, knaves who always lie, and spies (called normals by smullyan [sm78]) who can either lie or tell the truth. you encounter three people, a, b, and c. you know one of these people is a knight, one is a knave, and one is a spy. each of the three people knows the type of person each of other two is. for each of these situations, if possible, determine whether there is a unique solution and determine who the knave, knight, and spy are. when there is no unique solution, list all possible solutions or state that there are no solutions. 24. a says "c is the knave," b says, "a is the knight," and c says "i am the spy."

Alogical argument that is presented in graphical form using boxes and arrows is called?

Acircle has a circumference of 7.850 units. what is its radius?