Find the sum of the first 12 terms of the sequence. if the answer is negative, do not enter any spaces in between the number and the negative sign. 1, -4, -9, -14, . .

-318

Explanation:

The formula to use is

S = (n/2)*(2*a1+d*(n-1))

where

S = sum of the first n terms = unknown

n = number of terms = 12

d = common difference = -5

a1 = first term = 1

So we get the following

S = (n/2)*(2*a1+d(n-1))

S = (12/2)*(2*1 + (-5)*(12-1))

S = 6*(2 - 5(11))

S = 6*(2 - 55)

S = 6*(-53)

S = -318

The method to find the female dormitory is 2-d=800

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