中一數學題~

1. (xy三次方)(x三次方y二次方)
=X^4+XY^2+X^3Y^5+Y^5
2.化簡(-8x+5)+(-2x-7)
=-8X-2X+5-7
=-10X-2
=-2(5X+1)

3. .(3x-2y)(-5x+3y)
=-15X^2+9XY+10XY-6Y^2
=-15X^2+19XY-6Y^2

4. 643/82
~640/80
~8

5. -7,-10,-13,-16,-19, -22
= -7-3=-10-3=-13-3=-16-3=-19-3=-22

1.(xy三次方)(x三次方y二次方)
=x一次方+三次方y三次方+二次方
=x四次方y五次方

2.(-8x+5)+(-2x-7)
=-8x+5-2x-7
=-8x-2x+5-7
=-10x-2

3.(3x-2y)(-5x+3y)
=(3x-2y)(-5x)+(3x-2y)(3y)
=-15x二次方+10xy+9xy-6y二次方
=-15x二次方+19xy-6y二次方

4.643÷82
=640÷80
=8

5.general term= -3n-4

1.x三次方y六次方
2.-10x-2
3.-15 x二次方+19xy-6 y二次方
4.
5.

1.化簡(xy三次方)(x三次方y二次方)
= (xy³)(x³y²)
= (x^4)(y^5) //

2. 化簡(-8x+5)+(-2x-7)
= -8x + 5 - 2x - 7
= -6x - 2 //

3.(3x-2y)(-5x+3y)
= 3x(-5x+3y) - 2y(-5x+3y)
= -15x² + 9xy + 10xy - 6y²
= -15x² + 19xy - 6y² //

4. 使用相容數字，估算643÷82的值
643÷82
≈ 640 ÷ 80
= 8 //

5. 考慮以下的數列:-7,-10,-13,-16,-19,-22,猜出數列的通項
= -(4 - 3n) //

2007-01-11 18:06:35 補充：
第一題可以用指數定律找出答案 (a²)(a²) = a^(2+2)(a²)³ = a^(2x3)第二 、三題都係一些多項式的四則運算 (你 form 1 唔洗學除法)(+a) + (+b) = a + b(+a) - (+b) = a - b(-a) + (+b) = -a + b = b - a(-a) + (-b) = -a - b (+)(+) = +(+)(-) = (-)(-)(+) = (-)(-)(-) =(+)

2007-01-11 18:07:16 補充：
第四題, 將個數變成一些簡單的數即可 ( 但係個error不應太大, 1% - 5%都ok)第五題, 好難解釋點計~ 都係做多D maths exercises 啦~

2007-01-11 18:12:53 補充：
sorry~第二題錯左少少~2. 化簡(-8x 5) (-2x-7)= -8x 5 - 2x - 7 = -10x - 2 //這題唔洗 factorize佢 (即係第三位回答者的答案), -10x - 2 已經ok詳情請參考我其他的回答http://hk.knowledge.yahoo.com/question/?qid=7007010201415 (小提示)

2007-01-11 18:15:05 補充：
sorry~第五題, 唔記得轉符號答案應該係 -(4 + 3n) , 而唔係 -(4 - 3n)希望你對 form 1 數更明白~

2007-01-14 09:17:11 補充：
連第一題都計錯, 咁都做到最佳回答?