我有中2的數不明白
5(3m-n^2)^2-(n-3m)
=(3m-n)(15-5n +1)
點出來.同埋我想問(a-b)^2唔係=a^2-2ab+b^2
唔可以=(a+b)(a-b)
所以我想知個ans點出來
and有一條...
(2x-y)(a^2+b)-(b-a^2)(y-2x)
=2b(2x-y)
點出來.
MATHS FACTORIZATION
2010-07-24 11:32 am
回答 (2)
2010-07-24 3:07 pm
✔ 最佳答案
1. 5(3m -n)^2 - (n -3m) = 5(3m - n)^2 - [-(3m - n)] = 5(3m - n)^2 + (3m - n)= (3m - n)[5(3m - n) + 1] = (3m - n)(15m - 5n + 1).
2. (a - b) ^2 = (a - b)(a - b). It is NOT equal to a^2 - b^2 . [For example : (5 - 2)^2 = 9, not 5^2 - 2^2 ( = 25 - 4 = 21)]
Therefore, (a - b)^2 = (a - b)(a - b) = a^2 - 2ab + b^2, NOT a^2 - b^2, so NOT = (a + b)(a - b).
.3. (2x - y)(a^2 + b) - (b - a^2)(y - 2x)
= (2x - y)(a^2 + b) - (b - a^2)[-(2x - y)]
= (2x - y)(a^2 + b) + (b - a^2)(2x - y)
= (2x - y)[(a^2 + b) + (b - a^2)]
=(2x - y)(a^2 + b + b - a^2)
=(2x - y)(2b)
=2b(2x - y).
2010-07-24 10:35 pm
5(3m-n^2)^2-(n-3m)
I think you type wrong
_________________
It should be :
5(3m-n)^2-(n-3m)
5(n-3m)^2-(n-3m)
5(n-3m)(n-3m)-(n-3m)
(5n-15m)(n-3m)-(n-3m)
(n-3m)(5n-15m-1)
-(3m-n)(5n-15m-1)
(3m-n)(1-5n+15m)
_________________________
(n-3m)^2=(3m-n)^2
So, the sign do not need to change
2010-07-24 14:38:24 補充：
(2x-y)(a^2+b)-(b-a^2)(y-2x)
(2x-y)(a^2+b)+(2x-y)(b-a^2)
(2x-y)(a^2+b+b-a^2)
2b(2x-y)
I think you type wrong
_________________
It should be :
5(3m-n)^2-(n-3m)
5(n-3m)^2-(n-3m)
5(n-3m)(n-3m)-(n-3m)
(5n-15m)(n-3m)-(n-3m)
(n-3m)(5n-15m-1)
-(3m-n)(5n-15m-1)
(3m-n)(1-5n+15m)
_________________________
(n-3m)^2=(3m-n)^2
So, the sign do not need to change
2010-07-24 14:38:24 補充：
(2x-y)(a^2+b)-(b-a^2)(y-2x)
(2x-y)(a^2+b)+(2x-y)(b-a^2)
(2x-y)(a^2+b+b-a^2)
2b(2x-y)
收錄日期: 2021-04-25 22:37:49
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20100724000051KK00192