Question

Find the factor of 4x2

- 3x - 1​

Answer 1

Step-by-step explanation:

multiply the a and c terms

4

×

(

−

1

)

=

−

4

find factors of

−

4

that add to the b term, in this case

−

3

replace the b term with these two factors as coefficients

so the quadratic becomes

4

x

2

−

4

x

+

x

−

1

group the terms into pairs and factorise by grouping

(

4

x

2

−

4

x

)

+

(

x

−

1

)

4

x

(

x

−

1

)

+

(

x

−

1

)

(

4

x

+

1

)

(

x

−

1

)

If you work from the bottom of the page upwards you see the method is the reverse of multiplying out the brackets.