mrcy0becklittler mrcy0becklittler
  • 07-04-2017
  • Mathematics
contestada

What is the sum of 1 2 3 ... 81??

Respuesta :

LammettHash
LammettHash LammettHash
  • 07-04-2017
[tex]S=1+2+3+\cdots+79+80+81[/tex]
[tex]S=81+80+79+\cdots+3+2+1[/tex]

[tex]\implies 2S=(81+1)+(80+2)+\cdots+(2+80)+(1+81)[/tex]
[tex]\implies 2S=81(82)[/tex]
[tex]\implies S=81(41)=3321[/tex]
Answer Link

Otras preguntas

Deciduous forests can only be found in North America. True Or false? Please explai
out of the three states of matter which cannot be compressed on applying pressure
how did miranda v arizona expand civil rights
Rashau made a rectangular frame for her latest oil painting. The length is 28 centimeters more than triple the width. The perimeter of the frame is 136 centimet
can u help me with this problem 1/2+-2/5t-1=1/5t+t
In America the main influence of the enlightenment was expressed through
In 1962 President John F. Kennedy was faced with a decision to avoid nuclear war. What occurred to place the United States in that position?
Submerged basaltic volcanoes that are higher than 1 km are called
Three siblings sarah, Dave, and Kate - committed themselves to volunteer 155 hours for a homeless charity to build new housing. Kate worked 10 hours more than S
Two step equations with integers What is r/10+4=5. Please explain!