







An Euler diagram and a logic argument 
20080918 

From Regina: Use a Euler diagram to determine whether the following argument is valid or invalid.
No wizard can yodel
All lizards can yodel
No wizard is a lizard Answered by Penny Nom. 





A complex number in polar form 
20070723 

From roland: write the given complex number z in polar form lzl(p+qi) where lp + qil=1 for 3  4i. Answered by Harley Weston. 





Exponential form of complex numbers 
20070212 

From Austin: When dealing with imaginary numbers in engineering, I am having trouble getting things into the exponential form. The equation is 1+i now I do know that re^(theta)i = r*cos(theta) + r*i*sin(theta). Just not quite understanding the order of operations. Thanks Answered by Penny Nom. 





 n + 4  +  3  2n  = 16 
20020524 

From Randall: I don't seem to be able to solve this:  n + 4  +  3  2n  = 16 Answered by Penny Nom. 





An Invalid Argument 
19990531 

From Rod Redding: Can an invalid argument have a true conclusion? If yes then why? Answered by Walter Whiteley. 





A 
19990502 

From Leah: a=b a^2=ab a^2+b^2=abb^2 (ab)(a+b)=b(ab) a+b=b b 2=1 why is this proof wrong? Answered by Penny Nom. 

