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41 votes
41 votes
Factor 5x² + 8x – 4 using substitution.

User Bittersour
by
2.6k points

1 Answer

11 votes
11 votes

Answer:

(

5

x

2

)

(

x

+

2

)

is the factorised form of the expression.

Step-by-step explanation:

5

x

2

+

8

x

4

We can Split the Middle Term of this expression to factorise it.

In this technique, if we have to factorise an expression like

a

x

2

+

b

x

+

c

, we need to think of 2 numbers such that:

N

1

N

2

=

a

c

=

5

(

4

)

=

20

AND

N

1

+

N

2

=

b

=

8

After trying out a few numbers we get

N

1

=

10

and

N

2

=

2

10

(

2

)

=

20

, and

10

+

(

2

)

=

8

5

x

2

+

8

x

4

=

5

x

2

+

10

x

2

x

4

=

5

x

(

x

+

2

)

2

(

x

+

2

)

(

x

+

2

)

is a common factor to each of the terms

=

(

5

x

2

)

(

x

+

2

)

(

5

x

2

)

(

x

+

2

)

is the factorised form of the expression.

User Danny Tuppeny
by
2.7k points