Maths Presentation

If every pupil call individually early(a) on a mobile phone, how many calls lead thither be birthday suit when there are 910 pupils? Ok. So if two heap rang from each one(prenominal) other then it would look like this: =pupil 2 pupils=1 contacts =contact This shows that two people ordure precisely ring each other once. If 3 people rang each other, then it would look like this: and so on and so forth... 3 pupils= 3 contacts 4 pupils= 6 contacts If I refer all the combinations in up to six in a sequence then it would look like this: 2 3 4 5 6>>>>>>>>>> ordinal term 1 3 6 10 15>>>& gt;>>>> sequence 2 3 4 5 >>>>>>>>>>>difference 1 1 1 To find the nth term an2+bn+c II. 4a+2b+c=1 troika. 9a+3b+c=3 IV. 16a+4b+c=6 right away I am going to cancel show up the c by taking away equivalence II from tercet: V.

(9a+3b+c=6) (4a+2b+c=1) = (5a+b=2) Then I leave alone do the same for equation III and IV: VI. (16a+4b+c=6) (9a+3b+c=3) = 7a+b=3 Now to work out what a is, I will minus equation V from equation VI. VII. (7a+b=3) (5a+b= 2) = 2a=1 ! a=0.5 upon determination out that a equals 0.5, I can work out that... (5x0.5)+b=2 2.5+b=2 ...b=-0.5 So today I will go vertebral column to equation II to work out what c is: 4x0.5+2x-0.5+c=1 2+ (-1)+c=1 C=0 So the formula is: 0.5n2+ (-0.5n)=y So question asks how many calls would there be if 910 students called each other once. Now I can work out what it is by replacing n for 910: 0.5n2+ (-0.5n)=n(n+1)2=910(910+1)2=414 505If you insufficiency to get a honorable essay, order it on our website: OrderCustomPaper.com

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