Another sigma notation question. check. hopefully i did this one correctly!

Your answer is correct.  The series is a geometric series with common ratio -1/4 and first term 40.  So each term is:

an = 40 (-1/4)^(n−1)

So the sum of the first 10 terms is:

∑(n=1 to 10) [ 40 (-1/4)^(n−1) ]

answer with step-by-step explanation:

a. ∠j is supplementary to ∠k - true:

(opposite angles of a trapezoid are supplementary which means that they add up to 180 degrees)

b. kl is parallel to jm - true:

(opposite sides are parallel to each other in a trapezoid)

c. jk is perpendicular to kl - false:

(clearly, jk does not make a right angle with kl)

d. jk is parallel to lm - false:

(jk and lm are two lines opposite in direction to each other so they cannot be parallel)

e. ∠j is congruent to ∠m - true:

(the angles on each side of the base are congruent)

f. ∠j is congruent to ∠k - false:

(the angles on the same side but opposite side of the base are not congruent)

answer: 4

step-by-step explanation: