pinkrose1213
pinkrose1213 pinkrose1213
  • 16-06-2017
  • Mathematics
contestada

What is the 21st term of an arithmetic sequence with terms a6=50 and a11=85?

A. 125
B. 155
C. 185
D. 205

Respuesta :

mergl
mergl mergl
  • 16-06-2017
B.)155 

a1+d(n-1)
a1+d(6-1)=50
a1+5d=50
a1+d(11-1)=85
a1+10d=85
a1=50-5d
(50-5d)+10d=85
50-5d+10d=85
5d+50=85
5d=35
d=7
a1+7(6-1)=50
a1+35=50
a1=15
15+7(n-1)
15+7(21-1)
15+7(20)
15+140=155
Answer Link

Otras preguntas

Fill in the blank with the correct reflexive pronoun if necessary. If no pronoun is needed choose the X. Cuando era niña me gustaba ___ peinar a mi papá.
What colony was trying to simplify or purify the church of england?
For some reason my teacher gave this to us and I kinda forgot how to do this from last year... please helppp w/ work or she’s gonna kill me thank youuu
The main purpose of the following passage is to inform. What is its specific purpose? To assemble the swing set, you will need pliers; a Phillips screwdriver;
The ziggurat was associated with what feature of sumerian civilzation
A local sporting event charges $6 for each adult ticket and $3.50 for each child ticket. If the stadium sold a total of 65 adult and children’s tickets for a to
Compared to the Anti-Federalists, Federalists were which of the following selections? Select one: A. less fearful of the loss of individual rights B. all of th
what challenges do law enforcement agencies face in crime fighting and due process rights
50 POINTS #1-12 PLEASE have a great day☺️
which of the following behaviors would limit the risk of transmitting communicable diseases?A. engaging in sexual activity with multiple partnersB. ingesting co