Maths Question (Polynomials) 要列明步驟 =]

Shing Hin

2007-08-23 10:23 pm

1. Simplify (8m - 7m^2 + 3) - (m^2 - 2) + (1 + 8m^2 - 9m)

2. Expand (x^2 - 2x - 3)(x+5) and arrange the terms in descending powers of the variable.

3. Expand -2 (3k - 5)(5 - 3k)

4. Expand (x+5)(x+2)

要列明步驟 =].. THX =)

回答 (1)

Roger

2007-08-23 10:33 pm

✔ 最佳答案

1 Simplify
(8m - 7m² + 3) - (m² - 2) + (1 + 8m² - 9m)
= (-7 – 1 +8)m² + (8 – 9)m + (3 + 2 + 1)
= -m + 6

2. Expand (x² - 2x - 3)(x+5) and arrange the terms in descending powers of the variable.
= x(x² - 2x - 3) + 5 (x² - 2x - 3)
= x³ – 2x² - 3x + 5x² - 10x - 15
= -15 - 13x + 3x² + x³

3. Expand -2 (3k - 5)(5 - 3k)
= 2 (3k – 5)²
= 2(9k² - 30k +25)
= 18k² - 60k + 50

4. Expand (x+5)(x+2)
= x² + 7x + 10

2007-08-23 14:35:08 補充：
The answer of Q2 should be presented in descending power of x,= x³ 3x² - 13x - 15

2007-08-23 14:35:38 補充：
The answer of Q2 should be presented in descending power of x,= x³ + 3x² - 13x - 15

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