<span>n + (n + 1) + (n + 2) = 36
Let's first create the equation ourselves and then see if it fits any of the available options. We want 3 consecutive integers that add up to 36. Let's use the value "n" to represent the first number in the sequence.
n
Now the next number will be n+1 and the third will be n+2. And since we want the sum, we get
n + n + 1 + n + 2 = ?
And finally, we want the sum to be 36, so our final equation is
n + n + 1 + n + 2 = 36
With this equation in mind, let's look at the available choices.
n + (n + 2) + (n + 4) = 36
Well, it has the 36 OK, but it has +2 and +4 where we have +1 and +2. So it won't fit and it's wrong.
n + (n + 1) + (n + 3) = 36
Closer. Got the 36 and the +1. But it has +3 instead of +2, so not a fit either.
n + (n + 1) + (n + 2) = 36
This looks good. Has a couple of extra parenthesis, but they don't affect the final answer and it has the +1, +2 and the 36. This one is correct.
n + (n â’ 1) + (n â’ 3) = 36
Hmm. The n - 1 has a possibility. Perhaps they want n to be the middle of the 3 numbers to add. If that's the case, then the other number should be n+1 which it isn't. Maybe they want the n to be the last number. If that's the case, then the third number should be n-2. But that doesn't work either. So this equation won't work.
So of the 4 choices, the only answer that works is "n + (n + 1) + (n + 2) = 36"</span>
an = a1r^(n-1)
a5 = a1 r^(5-1)
-6 =a1 r^4
a2 = a1 r^(2-1)
-48 = a1 r
divide
-6 =a1 r^4
---------------- yields 1/8 = r^3 take the cube root or each side
-48 = a1 r 1/2 = r
an = a1r^(n-1)
an = a1 (1/2)^ (n-1)
-48 = a1 (1/2) ^1
divide by 1/2
-96 = a1
an = -96 (1/2)^ (n-1)
the sum
Sn = a1[(r^n - 1/(r - 1)]
S18 = -96 [( (1/2) ^17 -1/ (1/2 -1)]
=-96 [ (1/2) ^ 17 -1 /-1/2]
= 192 * [-131071/131072]
approximately -192
its easiest if you put it in y = mx + b form, where b is the number you plot on the y axis and m is your slope.
rearranging...
x + 3y = -5 3y = -x - 5 y = -1/3 x - 5/3
so your b value is -5/3, which is where you'll plot a point on the y axis. the slope is -1/3
since slope is rise over run, [and this case its negative] you'll go down 1 and to the right three.
edit: then draw a point there, connect the points, and you'll have a line =]
She will need 20 pages of stickers 10x20=200 just like 10x18=180 then 20-18=2 pages left
The average change per hour is B 40.7
