Recent content by EvenSteven

Find cov(Y,Z) where Y = 2X_1 - 3X_2 + 4X_3 and Z = X_1 + 2X_2 - X_3 Information given E(X_1) =4 E(X_2) = 9 E(X_3) = 5 E(Y) = -7 E(Z) = 26 I tried expanding cov(Y,Z) = E(YZ) - E(Y)E(Z) but can't figure out how to calculate E(YZ)

Area problem regarding r^2=8cos(2θ) and some other curve. I don't understand how to plot this. I started off with a table of values. I get confused when θ = π/2. I thought it would give r^2 = -8. But looking at mathematica it gives a leminiscate that crosses the origin. How come? Is it...

So are you saying we need to enunciate their name like it sounds in their native language? French is my first language and I wouldn't say Daycart is a wrong pronunciation. A lot of phonemes in french and other languages don't have an exact replica in english. Descartes in french sounds like...

Yes, thank you very much, figures I just had to use basic identify sin^2x = 1 - cos^2x and then simply factor to get to euler's answer. I definitely should have seen that.

So I'm trying to get through euler's introduction to the analysis of the infinite so I could eventually read his books on calculus but I'm stuck somewhere and can't seem to figure out how he equates this identity so by expanding I get sin(2y) * cos(z) + cos(2y) * sin(z). I get that the...