9. Find the sum of the first 6 terms of the sequence: –3, 1, 5, 9, . . . options: A) 25 B) 48 C) 42

C. 42.

Step-by-step explanation:

This is an arithmetic sequence with common difference d = 4 and first term a = -3.

Sum of n terms = (n/2)[2a + (n - 1)d]

Sum of  six terms = (6/2)[2(-3) + (6 - 1)4]

= 3 * (-6 + 20)

= 42.

C) 42

Step-by-step explanation:

Given is an Arithmetic Sequence, where

First term a = - 3

Common Difference d = 1-(-3)= 4

n = 6

a 4/6 = 9/12   not proportional

step-by-step explanation:

to find which are not proportional, we can use cross products

if it is true, they are proportional.   if it is not true, they are not proportional.

a 4/6 = 9/12

4* 12 = 6*9

48 = 54

not this is not proportional  

b 2/3 = 12/18  

2* 18 = 3 * 12

36 = 36

this is proportional

c 5/4 = 10/8  

5*8 = 4*10

40 = 40

this is proportional

d 7/5 = 35/25

7*25 = 5 * 35

175 = 175

is proportional

the answer is b: 18

step-by-step explanation:

use the pythagorean theorem to .

a^2+b^2=c^2

plug 18 for "r"

the 2 legs are 18 and 24

18^2+24^2=c^2

324+576=c^2

900=c^2

c=30

30-12=18

18 is the radius

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