因式分解(9) 送分

Ray

2009-01-17 8:02 am

1. x(a+b)+x(a+c)
2. x(2a+3b)+x(a+3b)
3. x(a+2b)+x(a+2c)
4. (a-b)(x^2-5)-(a-b)(3x+5)
5. 4x^2+4x+1

更新1:

第5題改改.... 5. 4x^2+4x+1-y^2

回答 (2)

老爺子

2009-01-17 10:23 am

✔ 最佳答案

1. x(a + b) + x(a + c)
1. = x[(a + b) + (a + c)]
1. = x(a + b + a + c)
1. = x(2a + b + c)

2. x(2a + 3b) + x(a + 3b)
2. = x[(2a + 3b) + (a + 3b)]
2. = x(2a + 3b + a + 3b)
2. = x(3a + 6b)
2. = 3x(a + 2b)

3. x(a + 2b) + x(a + 2c)
3. = x[(a + 2b) + (a + 2c)]
3. = x(a + 2b + a + 2c)
3. = x(2a + 2b + 2c)
3. = 2x(a + b + c)

4. (a - b)(x2 - 5) - (a - b)(3x+5)
4. = (a - b)(x + 5)(x - 5) - 3(a -b)(x + 5)
4. = (a - b)(x + 5)[(x - 5) - 3]
4. = (a - b)(x + 5)(x - 5 - 3)
4. = (a - b)(x + 5)(x - 8)

5. 4x2 + 4x + 1 - y2
5. = (4x2 + 4x + 1) - y2
5. = (2x + 1)2 - y2
5. = [(2x + 1) + y][(2x + 1) - y]
5. = (2x + y + 1)(2x - y + 1)
=

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Pan

2009-01-17 9:08 am

係咪

1. (2a+ b+ c)x
2. 3(a+ 2b)x
3. 2(a+ b+ c)x
4. (a- b)(x- 5)(x+ 2)
5. (2x+1+y)(2x+1-y)

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