急~有數學唔識做？？

其實只要你記住以下的式就可以做的了︰
a2 - b2 = (a + b)(a - b)
1. 6m2 - 9mn - 4m + 6n
= (6m2 - 4m) + (6n - 9mn)
= 2m(3m - 2) + 3n(2 - 3m)
= 2m(3m - 2) - 3n(3m - 2)
= (3m - 2)(2m - 3n)
2. a2 -4e2
= (a + 4e)(a - 4e) ← a2 - b2 = (a + b)(a - b)
3. 9m2 - n2
= (3m)2 - n2
= (3m + n)(3m - n) ← a2 - b2 = (a + b)(a - b)
這條題目，你是不是溜了一個(二次方)？
4. 9p2 - 49q2
= (3p)2 -(7q)2
= (3p + 7q)(3p - 7q) ← a2 - b2 = (a + b)(a - b)

因式分解

1.6m(2次方)-9mn-4m+6n
=32m-9mn+6n

2.a(2次方)-4e(2次方)
=(a-4e)(a+4e)

3.9m(2次方)-n2(2次方)
=(9m-n^2)(9m+n^2)

4.9p(2次方)-49q
=9p^2-7q^2
=(9p-7)(9p+7)