Given:
First term of an arithmetic sequence is 2.
Sum of first 15 terms = 292.5
To find:
The common difference.
Solution:
We have,
First term: 
Sum of first 15 terms: 
The formula of sum of first n terms of an AP is
![S_n=\dfrac{n}{2}[2a+(n-1)d]](https://tex.z-dn.net/?f=S_n%3D%5Cdfrac%7Bn%7D%7B2%7D%5B2a%2B%28n-1%29d%5D)
Where, a is first term and d is common difference.
Putting , n=15 and a=2 in the above formula, we get
![292.5=\dfrac{15}{2}[2(2)+(15-1)d]](https://tex.z-dn.net/?f=292.5%3D%5Cdfrac%7B15%7D%7B2%7D%5B2%282%29%2B%2815-1%29d%5D)
![292.5=\dfrac{15}{2}[4+14d]](https://tex.z-dn.net/?f=292.5%3D%5Cdfrac%7B15%7D%7B2%7D%5B4%2B14d%5D)
![292.5=15[2+7d]](https://tex.z-dn.net/?f=292.5%3D15%5B2%2B7d%5D)
Divide both sides by 15.
Dividing both sides by 7, we get
Therefore, the common difference is 2.5.
Answer: C
Step-by-step explanation:
They both end up equaling 4x+16 so they cancel each other out
To find the mean all you have to do is add all the numbers...
you should get -30
and divide by a number of numbers, there are 6
so -30/6 is -5
<h2><u>
Answer With Explanation:</u></h2>
<u>Firstly, let's start with <XOZ: =55°</u>
We know that <ZOQ is 70° and angles on a line add up to 180° so we do 180-70=110 110 divided by 2 = 55 so the 2 angles (XOZ & XOP are 55)
<u>Secondly, <OMN, <MON & <ONM = All are 60°</u>
These 2 angles are joined to create an equilateral triangle which always adds up to 180°
So, there are 3 points to this triangle, therefore we divide 180 by 3 which is 60. The angles are 60°
<u>Thirdly, <QON: =55°</u>
This angle lies on the line XON which needs to add up to 180°
As we worked out before, <XOZ was 55°
So, <ZOQ was already given as 70°
We then do 55+70=125 then 180-125=55°
<QON is 55°
(I'm only in Grade 9 LOL)
