Recent content by notSomebody

Homework Statement ∫\frac{4dx}{\sqrt{-4x - x^2}} Homework Equations arcsin(\frac{x}{a}) = \frac{1}{\sqrt{a^2-X^2}} Correct Answer: 4sin-1\frac{1}{2}(x + 2) + c The Attempt at a Solution I am completely lost with this one. I tried pulling a \sqrt{x} out of the bottom...

\frac{1- (-5)^{2+1}}{1- (-5)} = 21 though and not 25

Homework Statement 5^2 - 5^3 + 5^4 - ... + (-1)^k*5^k whre k is an integer with k >= 2 Homework Equations The Attempt at a Solution I know (5^(k-1) - 5^2)/2 gives you the sum if they were all positive. I tried multiplying it by (-1)^k or something but that just changes the sign. I...

Now I look foolish. I tried a couple of arrangements of numbers and it worked out, so I assumed it to be true. Thanks.

I'm at a loss here. I have no idea how to prove this. For all positive integers, k, m, n if k|mn then k|4m or k|4n. Homework Equations An integer r is divisible by an integer d if and only iff r=ds where s is some integer and d != 0. The Attempt at a Solution I tried rewriting the...