I realllllllyyy need help on this equation .

Question

mathmale · Answer

Dear Blessed:  Would you please post the actual question first?  what are your goals?

anonymous · Answer

$$\sum_{k=1}^{6} 42-n ^{2}$$

anonymous · Answer

Yes I was writing the equation @mathmale

anonymous · Answer

k=1 it looks like k-1 but its not
@mathmale

mathmale · Answer

$$\sum_{k=1}^{6} 42-n ^{2}, ~best~written~as~\sum_{k=1}^{6} (42-n ^{2}),$$

mathmale · Answer

may be easier to attack if you'd divide it up into 2 separate sums:

$$\sum_{k=1}^{6} 42-\sum_{k=1}^{6} n ^{2}$$

anonymous · Answer

okay so 
42-1^2
42-2^2
42-3^2
42-4^2
42-5^2
42-6^2

??

anonymous · Answer

is that correct?

mathmale · Answer

Take that 42 outside of the sum and write ' 1 ' in its place.  What is 42 times the sum of 1 from k=1 to k=6?

mathmale · Answer

$$\sum_{k=1}^{6} 42=42\sum_{k=1}^{6} 1=?$$

mathmale · Answer

There is a special formula for $$\sum_{k=1}^{6} n ^{2}.$$Do you know what it is?  Of course, if you prefer, you can simply find the squares of the numbers 1 thru 6 and then add them together.

anonymous · Answer

so the sum is 161?

anonymous · Answer

i forgot

mathmale · Answer

You've reached your conclusion via a different path, different from mine, I mean.  I have not done the actual work yet.

Have you any reference book or other material that lists basic summation formulas like those I've shown you?  They are well worth learning.

For example:

anonymous · Answer

I  have learned like 4 different ones and im not sure which one to use.

anonymous · Answer

im so confused

mathmale · Answer

$$\sum_{k=1}^{6} 1 = n = 6, \because n=6 ~here.$$

anonymous · Answer

so how would i solve it?

mathmale · Answer

There are at lest four basic formulas, for the sums, as i=1 thru n, of 1, n, n^2 and n^3.

Are these the formulas to which you're referring?

Nothing wrong with admitting that you're confused, but to obtain help quickly, y ou'll need to explain where and why you're confused and to ask questions that will get you back on track.

mathmale · Answer

If you've seen these summation formulas before in class, then you really do need to know them.

If you have $$\sum_{i=1}^{n}1$$ the sum is simply n.

$$\sum_{i=1}^{n}1=??~when~n=6??$$

mathmale · Answer

We're close to finding the solution to the problem you posted.  Please, if at all possible, stay with your helper(s) until you've found a solution.  OpenStudy says you're "just looking around."