One way of doing it is by using the properties of summing things, like factoring out the minus sign:
<span><span>∑<span>n=2</span>8</span><span>−(n−5)</span>=−<span>∑<span>n=2</span>8</span><span>(n−5)
</span></span>
and splitting it up into two parts and again factor
<span>=−<span>(<span><span>∑<span>n=2</span>8</span><span>n−5<span>∑<span>n=2</span>8</span>1</span></span>)
</span></span>
The last sum is just counting how many numbers there are from 2 to 8, which is 7 (you can do it on your fingers). The first one can be calculated fast if we are clever and use this identity:
<span><span>∑<span>n=1</span>m</span>n=<span><span>m(m+1)</span>2
</span></span>
So what we get is
<span><span>=−<span>(<span>−1+<span><span>8(8+1)</span>2</span>−7</span>)</span>=8−72/2=8−36=−28.</span></span>
1/3n * -6 = -2n
1/3n * 27m = 9nm
1/3n* -51p = -17np
-2n + 9nm - 17np
So where's the rest of the question?
1. (X-2) +6
2. I’ll figure that out when my brain starts working again
Since it is a line function, you just need two points to graph it.
So if you take x=0, you get y=0; which is the origin.
And when x=1, y=4.
You should get something like the attached picture.
