Why is 6, the answer?
Attachments:
Answers
Answered by
2
Answer:
number of points named are 6
Step-by-step explanation:
Let n be the number of points.
There are n points to start with. if we choose one point of n points, there are (n - 1) points left to choose from.You only need two points to define a ray (order matters).
So there are n*(n-1) unique rays.
Given, the student answered 30 rays in all and teacher said it was correct.
=> n(n - 1) = 30
=> n² - n - 30 = 0
=> n² - 6n + 5n - 30 = 0
=> n( n - 6) + 5(n - 6) = 0
=> (n - 6)(n + 5) = 0
=> n = 6 or - 5.
Since n cannot be negative, n = 6.
Thus the number of points named are 6.
Similar questions