Answer: Choice A
S9 = (9/2)*(2+26)
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The formula is
Sn = (n/2)*(a1+an)
where
Sn = sum of the first n terms (nth partial sum)
n = number of terms
a1 = first term
an = nth term
In this case,
n = 9
a1 = 2 (plug in n = 1 into the formula an = 3n-1 and simplify)
an = a9 = 26 (plug n = 9 into the formula an = 3n-1 and simplify)
So,
Sn = (n/2)*(a1+an)
S9 = (9/2)*(2+26)
will help us find the sum of the first 9 terms of this arithmetic sequence
The answer is D, because you move to the right of the decimal to see if that number is 5 or above. Then you round up, (to 86). :) Hope this was helpful.
Picture please!!!!!!!!!!!!!!!!!!!!!!
Step-by-step explanation:
25(2x) + 25(3y)
25 · (2 · x) + 25 · (3 · y)
(25 · 2) · x + (25 · 3) · y <em>Associative property </em><em>(a · b) · c = a · (b · c)</em>
(25 · 2)x + (25 · 3)y
(2 · 25)x + (3 · 25)y <em>Commutative property</em><em> a · b = b · a</em>
<em>50x + 75y</em>
