Need !
what is ∑ (3n−1) equal to?
n=18 is on bottom
8 is on top

So basically this is sigma, or summation notation, and if you still don't know what it is:

Start at the number on the bottom. Plug in that number to the equation on the right, plug in the next number into the equation on the right, and so on, until you get to the number on top. Plug in that final number, and after you get the solution, add all the solutions you have all together.
One thing though: the bottom number cannot be bigger than the number on top.

Plug in 1: 3 x (1) - 1 = 2
Plug in 2: 3 x (2) - 1 = 5
Plug in 3: 3 x (3) - 1 = 8

and so on. the pattern goes by +3

2 + 5 + 8 + 11 + 14 + 17 + 20 + 23 = 100

Answer is 100.

Intersecting secant-tangent theorem states that if a tangent segment and a secant segment are drawn to a circle from an exterior point, then the square of the measure of the tangent segment is equal to the product of the measures of the secant segment and its external secant segment.so to break it down: 1. pq acts as the tangent and ps as the secant with an intersection at p.sr = 21rp = 3x + 3pq = 4x + 4following to equation: tangent squared = the two segments multiplied by each otherso (4x + 4) ^ 2 = (3x + 3) • (21) simplifies to 16x^2 - 31x - 47 = 0 or (16x - 47)(x + 1) x = -1 or x = 47/162. pq acts as the tangent and ps as the secant with an intersection at p (again! )sr = 16rp = xpq = 15(15) ^ 2 = 16 • x225 = 16xx = 225/163. the interesting chords are proportional to each other so a ratio is possible to set up: ap dp 10 3 + x = = —— = pc pb 8 xcross multiple to get 10x = (3 + x)(8)x = 12