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第3,4題
數學問題~
2007-08-17 7:47 pm
回答 (3)
2007-08-17 7:58 pm
✔ 最佳答案
3) 2^(4x - 3) = (8^y) / 8
2^(4x - 3) = 8^(y - 1)
2^(4x - 3) = 2^3(y - 1)
4x - 3 = 3(y - 1)
4x = 3y
therfore y : x = 4 : 3
4)
(x + 3)(x + a) + b = x^2 + bx + 7
x^2 + (3 + a)x + (b + 3a) = x^2 + bx + 7
=>
3 + a = b ........(1)
b + 3a = 7 ......(2)
(1) into (2)
3 + a + 3a = 7
4a = 4
a = 1
a = 1 into (1)
3 + 1 = b
b = 4
Ans. a = 1, b = 4
2007-08-17 8:04 pm
3)
2^(4x - 3) = (8^y) / 8
2^(4x - 3) = 8^(y - 1)
2^(4x - 3) = 2^3(y - 1)
4x - 3 = 3(y - 1)
4x = 3y
x : y = 4 : 3
4)
(x + 3)(x + a) + b = x^2 + bx + 7
x^2 + (3 + a)x + (b + 3a) = x^2 + bx + 7
3 + a = b ........(1)
b + 3a = 7 ......(2)
Put (1) into (2)
3 + a + 3a = 7
4a = 4
a = 1
a = 1 into (1)
3 + 1 = b
b = 4
a = 1, b = 4
2^(4x - 3) = (8^y) / 8
2^(4x - 3) = 8^(y - 1)
2^(4x - 3) = 2^3(y - 1)
4x - 3 = 3(y - 1)
4x = 3y
x : y = 4 : 3
4)
(x + 3)(x + a) + b = x^2 + bx + 7
x^2 + (3 + a)x + (b + 3a) = x^2 + bx + 7
3 + a = b ........(1)
b + 3a = 7 ......(2)
Put (1) into (2)
3 + a + 3a = 7
4a = 4
a = 1
a = 1 into (1)
3 + 1 = b
b = 4
a = 1, b = 4
2007-08-17 7:56 pm
參考: My Maths knowledge
收錄日期: 2021-04-13 12:58:06
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20070817000051KK01483