Find the sum of the given arithmetic series. Do not just add, you must use the formula
What formula is used and how do I start this. I never seen this type of example as I only seen whole numbers used.
it is a very easy and simple issue
you just have to use the formula : the sum=number of terms over 2 times ("open brackets first term+last term)
here it is 6/2[1/2+(-12)]=-69/2
you are most welcomed
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