簡單 maths - Ans.fyi 參考答案

簡單 maths

Cindy

2007-08-07 9:25 am

1)(6^x+1)^2=2*3^(2x-1)
x=?
取有效數字３個位

答：－２．８８

2)(5/2)^x-1*(1/2)^x=25/2
x=?
取有效數字３個位

答：１５．４

3)2xz+4x^2-yz-y^2
答:(2x-y)(2x+y-z)

4.(u^2)(v^2)(1/u+1/v)^2
答:v^2+2uv+u^2

回答 (1)

用戶34881

2007-08-07 10:14 am

✔ 最佳答案

1)(6x+1)2=2*32x-1
(6x+1)2=2*32x-1
62x+2 = 2*32x-1
22x+232x+2 = 2*32x-1
22x+133 = 1
22x+1 = 3-3
(2x+1)log2 = log3-3
2x + 1 = -4.755
x = -2.88

2)(5/2)x-1*(1/2)x=25/2
(5/2)x-1*(1/2)x=25/2
(5/2)x-1*(1/2)x-1(1/2)=25/2
(5/4) x-1 = 25
(x – 1) log (5/4) = log25
x – 1 = 14.4
x = 15.4

3)2xz+4x2-yz-y2
2xz+4x2-yz-y2
= 4x2 + 2xy + 2xz – 2xy – y2 – yz
= 2x(2x + y + z) – y(2x + y + z)
= (2x – y)(2x + y + z)
你的答案不對。

4. (u2)(v2)(1/u+1/v)2
(u2)(v2)(1/u+1/v)2
= (u2)(v2)[(u + v)/uv]2
= (u2)(v2)[(u + v)/uv]2
= (u + v)2
= u2 + 2uv + v2

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