數學問題~唔該!!!高手come(代數式的運算)[要步驟]

全部都係展開啦@@
1.(x-8)(2x+1)
=x(2x+1)-8(2x+1)
=2x²+x-16x-8
=2x²-15x-8

2.(x-4)(x-5)
=x(x-5)-4(x-5)
=x²-5x-4x+20
=x²-9x+20

3.(2+y)(3+y)
=2(3+y)+y(3+y)
=6+2y+3y+y²
=y²+5y+6

4.(3-4y)(3+y)
=3(3+y)-4y(3+y)
=9+3y-12y-4y²
=9-9y-4y²

5.(3+2y)(4+y)
=3(4+y)+2y(4+y)
=12+3y+8y+2y²
=12+11y+2y²

6.(6+5y)(3+y)
=6(3+y)+5y(3+y)
=18+6y+15y+5y²
=5y²+21y+18

7.(3-2y)(4-y)
=3(4-y-)-2y(4-y)
=12-3y-8y+2y²
=2y²-11y+12

8.(3-4y)(5-7y)
=3(5-7y)-4y(5-7y)
=15-21y-20y+28y²
=28y²-41y+15

9.(x+2y)(x-y)
=x(x-y)+2y(x-y)
=x²-xy+2xy-2y²
=x²+xy-2y²


10.(3x+2y)(4x-y)
=3x(4x-y)+2y(4x-y)
=12x²-3xy+8xy-2y²
=12x²+5xy-2y²

11.(2x+5y)(4x+3y)
=2x(4x+3y)+5y(4x+3y)
=8x²+6xy+20xy+15y²
=8x²+26xy+15y²

12.(3x-2y)(4x-5y)
=3x(4x-5y) -2y(4x-5y)
=12x²-15xy-8xy+10y²
=12x²-23xy+10y²

1.(x-8)(2x+1)
=x(2x+1)-8(2x+1)
=2x二次方+x-16x-8
=2x二次方+17x-8

2.(x-4)(x-5)
=x(x-5)-4(x-5)
=x二次方-5x-4x+20
=x二次方-9x+20

3.(2+y)(3+y)
=2(3+y)+y(3+y)
=6+2y+3y+y二次方
=y二次方+5y+6

4.(3-4y)(3+y)
=3(3+y)-4y(3+y)
=9+3y-12y-4y二次方
=4y二次方-13y

5.(3+2y)(4+y)
=3(4+y)+2y(4+y)
=12+3y+4y+2y二次方
=2y二次方+7y+12

6.(6+5y)(3+y)
=6(3+y)+5y(3+y)
=18+6y+15y+5y二次方
=5y二次方+26y+18

7.(3-2y)(4-y)
=3(4-y)-2y(4-y)
=12-3y-8y+2y二次方
=2y二次方-11y+12

8.(3-4y)(5-7y)
=3(5-7y)-4y(5-7y)
=15-21y-20y+28y二次方
=28y二次方-41y+15

9.(x+2y)(x-y)
=x(x-y)+2y(x-y)
=x二次方-xy+2yx-2y二次方
=x二次方-2y二次方-2x*3y

10.(3x+2y)(4x-y)
=3x(4x-y)+2y(4x-y)
=12x二次方-3xy+2y4x-2y二次方
=12x二次方-2y二次方-7x*4y

11.(2x+5y)(4x+3y)
=2x(4x+3y)+5y(4x+3y)
=8x二次方+2x3y+5y4x+15y二次方
=8x二次方+15y二次方+6x*8y

12.(3x-2y)(4x-5y)
=3x(4x-5y)-2y(4x-5y)
=12x二次方-3x5y-2y4x+10y二次方
=12x二次方+10y二次方+x*3y

9-12題 不知對不對

1.(x-8)(2x+1)
x-8
x) 2x+1
------------
2x^2 - 16x
+) x -8
------------------
2x^2 - 15x -8



2.(x-4)(x-5)

x-4
x) x-5
------------
x^2 - 4x
+) -5x+20
_________________
x^2-9x+20




3.(2+y)(3+y)

2+y
x) 3+y
____________
6+ 3y
y^2+ 2y
____________
y^2+5y+6



4.(3-4y)(3+y)

3-4y
x) 3+y
_________
9-12y
3y-4y^2
__________
9-9y-4y^2



5.(3+2y)(4+y)

3+2y
x)4+y
_________
12+8y
3y+2y^2
_______
12+11y+2y^2



6.(6+5y)(3+y)

6+5y
x)3+y
________
18+15y
6y+5y^2
___________
18+21y+5y^2





7.(3-2y)(4-y)

3-2y
x) 4-y
___________
12-8y
-3y+2y^2
___________
12-11y+2y^2


8.(3-4y)(5-7y)

15-41y+28y^2


9.(x+2y)(x-y)

x^2+xy-2y^2


10.(3x+2y)(4x-y)

12x^2+5xy-2y^2


11.(2x+5y)(4x+3y)

8x^2+26xy+15y^2


12.(3x-2y)(4x-5y)

12x^2-22xy+10y^2

sorry,你答錯了,第1個答者,唔係多項式,係代數式!!

1.(x-8)(2X+1)
=x-8+2x+1
=x+2x-8+1
=3x-7

2.(x-4)(x-5)
=x-4+x-5
=x+x-4-5
=2x-9

3.(2+y)(3+y)
=2+y+3+y
=2+3+y+y
=5+2y