Math Is Fun Forum

Monox D. I-Fly

Member

From: Indonesia

Registered: 2015-12-02

Posts: 2,000

[ASK] Addition of a Fraction

Determine the value of

I know that it means

, but how do I answer? It's from a student worksheet for 7th graders, so they haven't learnt about sequence and series yet. Granted, the book also says that the question was from a middle school-level math contest.

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Actually I never watch Star Wars and not interested in it anyway, but I choose a Yoda card as my avatar in honor of our great friend bobbym who has passed away.
May his adventurous soul rest in peace at heaven.

Bob

Administrator

Registered: 2010-06-20

Posts: 10,621

Re: [ASK] Addition of a Fraction

hi

The denominators are 'triangle numbers' and there's a formula for those.

n(n+1)/2

Then you can use partial fractions to split each term into two fractions, one positive and one negative.

Most terms then cancel out.

Bob

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Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

Monox D. I-Fly

Member

From: Indonesia

Registered: 2015-12-02

Posts: 2,000

Re: [ASK] Addition of a Fraction

That confirms me that it's definitely not supposed to be for a 7th grader.

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Actually I never watch Star Wars and not interested in it anyway, but I choose a Yoda card as my avatar in honor of our great friend bobbym who has passed away.
May his adventurous soul rest in peace at heaven.

Bob

Administrator

Registered: 2010-06-20

Posts: 10,621

Re: [ASK] Addition of a Fraction

Actually it is possible to do the steps just with fractions:

The second term in each bracket cancels with the first term in the next.

Bob

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Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

Monox D. I-Fly

Member

From: Indonesia

Registered: 2015-12-02

Posts: 2,000

Re: [ASK] Addition of a Fraction

Actually it is possible to do the steps just with fractions:

The second term in each bracket cancels with the first term in the next.

Bob

darn, never thought of that! Now, THIS is beautiful! Thanks, bob bundy!

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Actually I never watch Star Wars and not interested in it anyway, but I choose a Yoda card as my avatar in honor of our great friend bobbym who has passed away.
May his adventurous soul rest in peace at heaven.