Which summation formula represents the series below?
1 answer:
Answer:
Step-by-step explanation:
The summation formula ( arithmetic sequence when the first terme is : A1 = 13
and the coomo diff is d= -4
Sn = n/2(A1 +An)
An = A1+(n-1)d
An = 13 +(n-1)(-4)
An = -4n +17
Sn = n/2(13+17-4n) = n/2(30-4n)
Sn = -2n² +15n
in this exercice : n =4 S4 = -2(4)² +15(4) = -32+60 = 28
verify : 13 + 9 + 5 + 1 =28 ......right
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Answer:
Step-by-step explanation:
-2+y=14
-5x-7y=10
y=14+2
y=16
-5x-7(16)=10
-5x-112=10
+112 +112
-5x=122
x=-24.4
I have no idea what this is
Answer:
Step-by-step explanation:
6. Use PEMDAS
-3 x (7 + (-3)*2) / 3
-3 x (7 + 9) / 3
-3 x 16 / 3
-48 / 3
-16
7. 9 (x) = -63
X = - 63 /9
X = -7
This is the answer
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