我想你地幫我解答這幾條因式分解的題目！

1.
3m-12n
3 ( m - 4n)


2.
-ab-2ac
= -a ( b + 2c)


3.
ab+bc+bd
= b (a + c + d)


4.
xy+y+x+1
= x( y + 1) + (y + 1)
= (y + 1) (x + 1)


5.
mr-nr+5m-5n
= r ( m - n) +5 ( m- n)
= (r + 5) ( m - n)


6.
(3x-4y)(3x+4y)
= 9x^2 - 16y^2
= (3x-4y)(3x+4y)

1. 3m-12n
=3(m-4n)

2. -ab-2ac
=-a(b+2c)

3. ab+bc+bd
=b(a+c+d)

4. xy+y+x+1
=y(x+1)+x+1
=(x+1)(y+1)

5. mr-nr+5m-5n
=r(m-n)+5(m-n)
=(m-n)(r+5)

6. (3x-4y)(3x+4y)
已經因式分解左la~

3(m-4n)
-a(b+2c)
b(a+c+d)
(x+1)(y+1)
(m-n)(r+5)
9x^2-16y^2