Summing arithmetic series (1 Viewer)

[enigma_1]

hey guys how do you do these? Thanksss a lot!!

 

[asianese]

What is an odd number? Hence what are the odd multiples of 100?

 

[Chris100]

Use the formula
S=n/2(a+l) for the bottom question
answer should be 10 trips, 1km apart

 

[enigma_1]

What is an odd number? Hence what are the odd multiples of 100?

Aren't multiples of 100 these: 100, 200, 300 .... How can they be odd?

 

[RealiseNothing]

Aren't multiples of 100 these: 100, 200, 300 .... How can they be odd?

yer... no idea

 

[braintic]

Aren't multiples of 100 these: 100, 200, 300 .... How can they be odd?

You are parsing the sentence incorrectly.

It should be "the (odd multiples) of 100", not "the odd (multiples of 100)"

 

[enigma_1]

whaaaaaat thhe ^

 

[asianese]

...

Odd multiples of 100:



In HSC terms:

x is 100 multiplied by y, where y is an odd number ranging from 1, 3, 5...

 

[RealiseNothing]

So like... and and etc?

b10 by above

 

[bokat]

The solution for 6d is as follows.
By odd multiples of 100 they mean: 1x100, 3x100, 5x100 etc.
So the terms are 100,300,500,....,(2n-1)x100
The term no. n being (2n-1)x100 ,a=100 and d=200
Using the sum formula s=n/2(2a+(n-1)d) we get:
s=n/2(2x100+(n-1)200) which gives s=100 x n^2

I hope it is clear.

Reza Bokat,
Cambridge Coaching
Cambridge Coaching

 

[braintic]

whaaaaaat thhe ^

Is that a question?

 

[asianese]

Is that a question?

Yeah - she doesn't understand bracketing in English.

 

[RealiseNothing]

Yeah - she doesn't understand bracketing in English.

The question is ambiguous and poorly worded though. It should have been expressed better.

 

[asianese]

The question is ambiguous and poorly worded though. It should have been expressed better.

There's no doubting this, but there really were only 2 options and one was clearly not possible (100 being odd)