<<急急急>>數學問題!

2009-06-01 4:48 am
1) (2a-3b)(-2)
2) (x+4y+5z)a
3) (a+2b)(2a+3b)
4) (5m+4n)(m-4n)
5) (3a+2b)(3a-2b)
6)Expand (1+x)(3-4x) and arrange the terms descending power of x.

*要有步驟!THX!
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更新1:

唔晒大家!>\/

更新2:

係唔該晒~ =]

回答 (4)

2009-06-01 4:56 am
✔ 最佳答案
1.-2*2a-2*(-3b)
=-4a+6b

2.a*x+a*4y+a*5z
=ax+4ay+5az

3.a*(2a+3b)+2b*(2a+3b)
=2a^2+7ab+6b^2

4.5m*(m-4n)+4n*(m-4n)
=5m^2-16mn-16n^2

5.3a*(3a-2b)+2b*(3a-2b)
=9a^2-4b^2

6.1*(3-4x)+x(3-4x)
=3-4x+3x-4x^2
=-4x^2-4x+3

2009-05-31 20:57:27 補充:
自己寫返題目=w="
參考: 自己計=.=
2009-06-01 5:17 am
1) (2a-3b)(-2)
=2a(-2)+(-3b)(-2)
= -4a+6b



2) (x+4y+5z)a
=x(a)+4y(a)+5z(a)
=xa+4ya+5za



3) (a+2b)(2a+3b)
=a(2a)+a(3b)+2b(2a)+2b(3b)
=2a 2次方+3ba+4ba+6b 2次方
=2a 2次方+7ba+6b 2次方



4) (5m+4n)(m-4n)
=5m(m)+5m(-4n)+4n(m)+4n(-4n)
=5m 2次方-20mn+4mn-16n 2次方
=5m 2次方-16mn-16n 2次方



5) (3a+2b)(3a-2b)
=3a(3a)+3a(-2b)+2b(3a)+2b(-2b)
=9a 2次方-6ab+6ab-4b 2次方
=9a 2次方-4b 2次方



6) (1+x)(3-4x)
=1(3)+1(-4x)+x(3)+x(-4x)
=3-4x+3x-4x 2次方
=-4x 2次方-4x+3x+3




咁得唔得???
p.s有一d數有 2次方....
but我打5到....
所以我就打 [ 2次方]3個字...
5好意思...睇的時候有d煩...
sorry about that...
參考: my own knowledge...
2009-06-01 4:59 am
1. -4a + 6b
2. ax+4ay+5az
3. 2a^2+3ab+4ab+6b^2 = 2a^2+7ab+6b^2
4. 5m^2-20mn+4mn-16n^2 = 5m^2-16mn-16n^2
5. 9a^2-6ab+6ab-4b^2 = 9a^2-4b^2
6. 3-4x+3x-4x^2 = -4x^2-x+3
參考: me :)
2009-06-01 4:59 am
1. - 4a+6b

2. ax+4ay+5az

3.2a^2+7ab+6b^2

4.5m^2-16nm-16n^2

5.9a^2 - 4b^2

6. - 4x^2- x+3
參考: me


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