find the solution!!!!!!

Question

anonymous · Answer

$$\sin^{-1} \frac{ \sqrt{2}\ }{ 2}$$

anonymous · Answer

Sin is equal to $\frac{\sqrt{2}}{2}$ when its angle is $\frac{\pi}{4}$, so that's your answer.

anonymous · Answer

ok thanks

anonymous · Answer

is therea solution to this
Find the sum of the geometric sequence 100, 50, 25,…

anonymous · Answer

Yes.  You should memorize the sum of an infinite geometric series: $\frac{a_1}{1-r}$.  Your first time ($a_1$) is 100, and the ratio is $\frac{1}{2}$, so the sum is $\frac{100}{1-\tfrac{1}{2}} = 200$.

anonymous · Answer

ok what about this one
Find the sum of the first 31 terms of the sequence 12, 10, 8, …

anonymous · Answer

is the answer 84 or 1302?

anonymous · Answer

That's an arithmetic series, which you sum by $\frac{n\left(a_1+a_n\right)}{2}$.  $n=31$, and the last term will be $12-2\cdot30=-48$, so you have $\frac{31(12-48)}{2}=-558$ is your sum.

anonymous · Answer

I'm assuming they mean the sequence is 12,10,8,6,4,2,0,-2,-4, etc.

anonymous · Answer

oh ok  and yes so i must have calculated wrong