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

Help me please please
Julie is keeping stats for the baseball team. In 4 games, they scored 36 runs. What is the average number of runs for the 4 games? Enter your answer
someone help please! HURRYY!!
Who works in each place? Make sentences with the words in Exs laand 3.doctors and nurses work a hospitalproszę o pomoc daje naj​
This is the graph of f(x). What is the value of (2)? 101Y х -5 5 5 O A. 16 B. 2. O C. 8 O D. 4
A heat engine uses thermal energy that flows from a heat source with a temperature of 325k to a cold sink that has the temperature of 135k what is the efficienc
can you relate this lesson to your real-life situation ​
Can somebody help me real quick
What is the hypotenuse? What letter represents the hypotenuse in the formula? How can we always identify the hypotenuse?
The point (8, 0) lies on a circle with the center at the origin. What is the area of the circle to the nearest hundredth? Use 3.14 for (pi).