急!!!!!有幾條數學唔識做!!!幫吓我!!!!!!

1. (2x+3y)4
=8x+12y
2.(1+1.5x)(2-3x)
=2-3x-3x-4.5x²
=4.5x²-6x+2
3. 2(k+3)(3k-2)
=(2k+6)(3k-2)
=6k²-4k+18k-12
=6k²+14k-12
=2(3k²+7k-6)
4. (y-2z)(2z+3y)
=2yz+3y²-4z²-6yz
=3y²-4z²-4yz
5. (3t-2)(1+2t)-(6t-1)(t+5)
=(3t+6t²-2-4t)-(6t²+30t-t-5)
=(6t²-t-2)-6t²-30t+5
=31t+3
希望幫到你！！

2007-07-30 16:19:39 補充：
請更改第 2 及 第 5 題：2. (1 1.5x)(2-3x)= 2-3x 3x-4.5x²= -4.5x² 25. (3t-2)(1 2t)-(6t-1)(t 5)= (3t 6t²-2-4t) - ( 6t² 30t-t-5)= (6t²-t-2) - (6t² 29t-5)= 6t²-t-2-6t²-29t 5= 30t 3= 3(10t 1)

2007-07-30 16:22:09 補充：
5. (3t-2)(1 2t)-(6t-1)(t 5)= (3t 6t²-2-4t) - ( 6t² 30t-t-5)= (6t²-t-2) - (6t² 29t-5)= 6t²-t-2-6t²-29t 5= -30t 3= 3(-10t 1)

1. (2x+3y)4
= 8x + 12y

2. (1+1.5x)(2-3x)
= 2 + 3x - 3x - 4.5x^2
= 2 - 4.5x^2

3. 2(k+3)(3k-2)
= 2(3k^2 + 9k -2k -6)
= 6k^2 + 14k -12

4. (y-2z)(2z+3y)
= 2yz - 4z^2 + 3y^2 -6yz
= 3y^2 - 4z^2 - 4yz

5. (3t-2)(1+2t)-(6t-1)(t+5)
= (3t - 2 + 6t^2 - 4t) - (6t^2 - t + 30t - 5)
= (6t^2 - t -2) - (6t^2 + 29t -5)
= -30t +3
= 3(-10t +1)

2007-07-30 16:20:18 補充：
樓上 2) & 5)..好似爭少少喎...

2007-07-31 00:35:28 補充：
4(y-2z)(2z 3y)= 4(2yz - 4z^2 3y^2 -6yz)= 4(3y^2 - 4z^2 - 4yz)= 12y^2 16z^2 - 16yz