Answer:
Step-by-step explanation:
The formula for determining the sum of the first n terms of an arithmetic sequence is expressed as
Sn = n/2[2a + (n - 1)d]
Where
n represents the number of terms in the arithmetic sequence.
d represents the common difference of the terms in the arithmetic sequence.
a represents the first term of the arithmetic sequence.
If a = 5, the expression for the sum of the first 12 terms is
S12 = 12/2[2 × 5 + (12 - 1)d]
S12 = 6[10 + 11d]
S12 = 60 + 66d
Also, the expression for the sum of the first 3 terms is
S3 = 3/2[2 × 5 + (3 - 1)d]
S3 = 1.5[10 + 2d]
S3 = 15 + 3d
The sum of the first 12 terms is equal to ten times the sum of the first 3 terms. Therefore,
60 + 66d = 10(15 + 3d)
60 + 66d = 150 + 30d
66d + 30d = 150 - 60
36d = 90
d = 90/36
d = 2.5
For S20,
S20 = 20/2[2 × 5 + (20 - 1)2.5]
S20 = 10[10 + 47.5)
S20 = 10 × 57.5 = 575
8.57 for the first one and, I’m not sure a bout the second time though
She has $55. She spent $22.50 on rides so now she has $32.50 . Then she spends $14.25 on lunch and snack so now she has $18.25.
A. would be wrong because Courtney IS correct, she has $18.25 left.
C. is also wrong because, again, Courtney IS correct.
So the only option left is B and it explains why Courtney is correct.
Option B is the correct answer.
Hope this helps.
Answer:
64 1/2
Step-by-step explanation:
5x12=60
3/8x12/1= 36/8= 9/2 9/2=4 1/2
60+4 1/2= 64 1/2
Slope = (y₂-y₁)/(x₂-x₁)
by making (x₁,y₁) = (-2,2) and (x₂,y₂) = (5,3)
∴The slope = (3-2)/(5 - -2) = 1/7