factorising help

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So what is the best way of factorising a quadratic that has something behind the

x^2

Reply 81

TenOfThem

Original post by zed963

So what is the best way of factorising a quadratic that has something behind the

x^2

There is no best way

it is about practice, looking for patterns, knowing factors, being willing to try numbers, etc

Reply 82

steve2005

Original post by zed963

So what is the best way of factorising a quadratic that has something behind the

x^2

Practice Practice and then some more practice.

Here is one method. Getting the list of pairs is easier than it might at first appear. Suppose the product was 96, then the first pair would be (1)(96) then double the ONE and half the 96, then multiply the ONE be 3 and divide the 96 by 3.

Use your brain to find short cuts.

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Reply 83

zed963

So if I was to factorise

(2d+1)^2+(2d+1)

Would it be

(2d+1)[1+(2d+1)+1]=2d+2

so it becomes

(2d+1)(2d+2)

but when I check in the back of the book it says

2(d+1)(d+1)

Reply 84

steve2005

Original post by zed963

So if I was to factorise

(2d+1)^2+(2d+1)

Would it be

(2d+1)[1+(2d+1)+1]=2d+2

so it becomes

(2d+1)(2d+2)

but when I check in the back of the book it says

2(d+1)(d+1)

NO

Do you know what this sign means =

Reply 85

zed963

Original post by steve2005

What "no"?

Reply 86

steve2005

Original post by zed963

What "no"?

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Reply 87

zed963

Original post by steve2005

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What have you done on the 4th line?

Reply 88

steve2005

Original post by zed963

What "no"?

Sometimes you can easily check whether you have written rubbish.

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Reply 89

steve2005

Original post by zed963

What have you done on the 4th line?

2 is a factor of the second bracket.

Reply 90

zed963

Original post by steve2005

Sometimes you can easily check whether you have written rubbish.

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I'm not understanding?

Why do we need the 4th line?

Reply 91

zed963

Original post by steve2005

2 is a factor of the second bracket.

But its not for the whole bracket though

Reply 92

TenOfThem

Original post by zed963

But its not for the whole bracket though

2 is a factor of the bracket (2d+2)

So (2d+2) = 2(d+1)

Reply 93

zed963

Original post by TenOfThem

2 is a factor of the bracket (2d+2)

So (2d+2) = 2(d+1)

but if u were going to divide it by 2 wouldn't u do it with two brackets

Reply 94

TenOfThem

Original post by zed963

but if u were going to divide it by 2 wouldn't u do it with two brackets

I (and Steve) am not dividing by anything

but no I would not do it to both brackets

3x14 = 3x(2x7) = 2x3x7

a(2b+4) = a2(b+2) = 2a(b+2)

(a+1)(2b+4) = (a+1)2(b+2) = 2(a+1)(b+2)

Reply 95

zed963

Original post by TenOfThem

I (and Steve) am not dividing by anything

but no I would not do it to both brackets

3x14 = 3x(2x7) = 2x3x7

a(2b+4) = a2(b+2) = 2a(b+2)

(a+1)(2b+4) = (a+1)2(b+2) = 2(a+1)(b+2)

All right I understand.

Reply 96

steve2005

Original post by mahnoorbloch

In this Question you have to open the squares and then solve them normally.
For free online Education and free physics notes check this*http://www.notes4all.com

There are several ways of simplifying this expression. There is no SOLVING involved because it is not an equation.

Here I am using the Difference of two squares.

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Reply 97

steve2005

Original post by mahnoorbloch

take x +3y form both sides than i will easy to solve the question.
For free*online education*and free physics notes check this*http://www.notes4all.com

no no no

Reply 98

steve2005