Lesson EXAMPLES - Factoring

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This Lesson (EXAMPLES - Factoring) was created by by longjonsilver(2297) About Me : View Source, Show
About longjonsilver: I have a new job in September, teaching

FACTORISATION EXAMPLES

Factorise the following:

1. 2xy+-+12y
Visualise this as 2*x*y - 2*6*y.

What is common to both terms? Answer is 2.
What is left in both terms once the 2 is removed? Answer is xy - 6y

--> answer is: 2(xy - 6y)

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2. 5m%5E2+%2B+10mn
Visualise this as 5*m*m + 5*2*m*n

What is common to both terms? Answer is 5*m
What is left in both terms once the 2 is removed? Answer is m + 2*n

--> answer is: 5m(m + 2n)

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3. 6x%5E5+-+3xy%5E2+%2B+9x%5E2
Visualise this as 3*2*x*x*x*x*x - 3*x*y*y + 3*3*x*x

What is common to both terms? Answer is 3*x
What is left in both terms once the 2 is removed? Answer is 2*x*x*x*x - y*y + 3*x

--> answer is: +3x%282x%5E4+-+y%5E2+%2B+3x%29+

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4. x%5E4y%5E3+-+x%5E3y%5E2+%2B+x%5E2y%5E5
Visualise this as x*x*x*x*y*y*y - x*x*x*y*y + x*x*y*y*y*y*y

What is common to both terms? Answer is x*x*y*y
What is left in both terms once the 2 is removed? Answer is x*x*y - x + y*y*y

--> answer is: +x%5E2y%5E2%28x%5E2y+-+x+%2B+y%5E3%29+

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5. ab%5E2c%5E2+%2B+a%5E2b%5E3c%5E2+-+a%5E4b%5E2c+%2B+a%5E5b%5E4c%5E3
Visualise this as a*b*b*c*c + a*a*b*b*b*c*c - a*a*a*a*b*b*c + a*a*a*a*a*b*b*b*b*c*c*c

What is common to both terms? Answer is a*b*b*c
What is left in both terms once the 2 is removed? Answer is c + a*b*c - a*a*a + a*a*a*a*b*b*c*c

--> answer is: +ab%5E2c%28c+%2B+abc+-+a%5E3+%2B+a%5E4b%5E2c%5E2%29+

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Summary
You will not get harder versions of factorisations of this type than these.

The skill is to just look at the question and figure it out without writing the terms in the long-winded expanded versions I used above...the "Visualise" part. I only showed you this to explain what the terms actually mean and how to think about "common factors".

All this comes with practice and understanding such things as powers/exponents.

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