Уроки математики и физики (RU + UA)

воскресенье, 16 апреля 2017 г.

Lesson 11. Common factors

We know that

3(a + b)

is we same as

3a + 3b

so

3a + 3b = 3(a + b)
3 is a factor of both 3a and 3b
so 3 is the common factor of 3a and 3b
Common factors can be extracted from algebraic expressions.
Take out common factor 3.
This is called ‘factorising’

3a + 3b

EXAMPEL:

Factorise

7x – 7y

7x and 7y have common factor 7
so

7x – 7y = 7(xy)

EXAMPEL:

Factorise

5a + 10b

5 divides into 5a and 10b
so 5a and 10b have common factor 5
so 5a + 10b = 5(a + 2b)

Letters as well as numbers can be the common factors.

EXAMPEL:

Factorise

ab + ac
ab and ac have common factor a
So
ab + ac = a(b + c)

multiply out to check the answer is correct

EXAMPEL:

Factorise

5ac + 15bc

5ac and 15bc have common factor 5c so

5ac + 15bc = 5c(a + 3b)

EXAMPEL:

Factorise
4x26x
4x2 and 6x have common factor 2x so
4x26x = 2x(2x – 3) 

Lesson 11

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