Factorise the following: 4m(m+3)+3(-m-3)?

2009-09-22 12:24 pm

4m(m+3)+3(-m-3)

Just doing some home studying for college after 2 years away from school, so I need some advice on how to do the above :) Thanks.

更新1:

Thank you, I have looked through and all is clearer on the know how. Just need to know now why you all have changed the +3 outside the brackets to a -3 ( and the same inside the brackets)

回答 (5)

[匿名]

2009-09-22 12:27 pm

✔ 最佳答案

4m(m+3)+3(-m-3) =

4m(m + 3) - 3(m + 3) =

(4m - 3)(m + 3)

Edit : good question, in + 3( - m - 3) if you factor - 1 then you'll get - 3(m + 3)

they are still the same check:

+ 3( - m - 3) = - 3m - 9

- 3(m + 3) = - 3m - 9

Now the reason for this is to make (m + 3) common factor.

👍 2 👎 1

[匿名]

2009-09-22 8:29 pm

= 4m(m + 3) + 3(- m - 3)
= 4mÂ² + 12m - 3m - 9
= 4mÂ² + 9m - 9
= (4m - 3)(m + 3)

Answer: (4m - 3)(m + 3)

👍 3 👎 0