agentkronus
agentkronus agentkronus
  • 02-03-2015
  • Mathematics
contestada

Find x when P = 21.

P = x(x - 1) / 2

Respuesta :

konrad509
konrad509 konrad509
  • 02-03-2015
[tex]21=\dfrac{x(x-1)}{2}\\ 42=x^2-x\\ x^2-x-42=0\\ x^2+6x-7x-42=0\\ x(x+6)-7(x+6)=0\\ (x-7)(x+6)=0\\ x=7 \vee x=-6[/tex]
Answer Link

Otras preguntas

Which of these correctly describes what happens to the molecules in a BOWL OF ICE CREAM when it melts? A - They absorb heat energy and start moving more slowly
Question 1 (1 point) The First Battle of Bull Run was considered a a difficult victory for the Union. b an easy victory for the Union. c a setback for the Un
What was the objective that the green mountain boys were going to accomplish
What is the value of cos(60)
A teacher polled only the 8th grade students in English classrooms on what their favorite color is. She found that the favorite color of the school is blue. Wha
What is the rhyme scheme in this poem? if i were you i wish we could change shoes because i would make you feel unpretty too i was told i was beautiful but wha
Find tan(B) in the triangle. Choose 1 answer A 15/8 B 8/17 C 8/15 D 15/17
Mr. Ruckman is a small business owner that is thinking about expanding his business. In his college and younger years, he struggled financially which ruined his
An object initially at rest experiences an acceleration of 9.8m/s2. How much time will it take it to achieve a velocity of 49m/s?
Can someone help please?