Answer:
17) 26
18) 66
19) 78
20) 145
Step-by-step explanation:
#17) 8 + 3n for n = 6
8 + 3*(6)
8 + 18 = 26
#18) (8 + 3)n for n = 6
(8 + 3)*6
(11)*6 = 66
#19) 90 - 4d for d = 3
90 - 4*(3)
90 - 12 = 78
#20) 7x + 2y for x = 15, y = 20
7*(15) + 2*(20) = 145
1 over 7 to the 2nd power
Answer: put dot on A B And C the put them together. And that the answer for 2
Step-by-step explanation:
Answer:
225
Step-by-step explanation:
The sum of this series is given by the formula:
![S_n=\frac{n}{2}[2a+(n-1)d]](https://tex.z-dn.net/?f=S_n%3D%5Cfrac%7Bn%7D%7B2%7D%5B2a%2B%28n-1%29d%5D)
Where
S_n is the sum
a is the first term (we get this by plugging in n = 1 into "2n-1", we have 2(1) - 1 = 1)
n is the number of terms (the sum is defined for n = 1 to n = 15, so 15 terms)
d is the common different (the difference is successive terms. Here, 2nd term would be 2(2) - 1 = 3, and first term was 1, so d = 3 -1 = 2)
<em>plugging in the info, we will get the sum:</em>
<em>
</em>
<em>The sum is 225</em>