# Yahoo奇摩 網頁搜尋

1. ### how to calculate total surface area？?

...you just need to add all area of the faces, much easy right? So you can don 't use any of formula, just work for a long time to find the area of each faces...

分類：科學及數學 > 數學 2021年01月21日

2. ### Maths: how to do, thanks. I don 't know how to do (b).?

(a) f(x)=2x^3+ax^2+7x-9x=1f(1)=00=2+a+7-9a=0f(x)=2x^3+7x-9(bi)Area of OPQR=m(4m^2 +14)=4m^3+14m(bii)18=4m^3+14m2m^3+7m-9=0m=1 I agree

分類：科學及數學 > 數學 2021年01月03日

3. ### Trig question, what have I don 't wrong? Solve (tan(2x)-tan(x))*(cos(3x)+cos(x))+2*cos(x)=2?

Question： Solve [tan(2x) - tan(x)][cos(3x) + cos(x)] + 2cos(x) = 2, 0 ≤ x ≤ π Solution： [tan(2x) - tan(x)][cos(3x) + cos(x)] + 2cos(x) = 2, 0 ≤ x ≤ π  ... sin x + cos x = 1 (sin x + cos x)² = 1 ...... [ It also implies (sin x + cos x)² = (-1)² ] ... x = 0, π...

分類：科學及數學 > 數學 2021年01月11日

4. ### Maths problem how to do, thanks?

兩題都不能完全算出結果, 只能用 k 的函數表示. Let k be a constant. If the roots of the quadratic equation x^2-5x+k = 0 are α and β, find α^3β+5αβ^2. [Sol.] α^3β+5αβ^2     = αβ(α^2-5α+k)+5α^2β-kαβ+5αβ^2     = 5αβ(α+β)-kαβ     = 5k(5) - k(k)     = 25k-k^2 = k(25-k...

分類：科學及數學 > 數學 2020年11月17日

5. ### Maths problem: i don 't know how to do (c), it's so difficult, thanks?

(a) P(red) = x/48 = 1/16, so x = 48/16 = 3. P(yellow) = y/48 = 1/12, so y = 48/12 = 4. (b) The number of black balls is 48 - x - y = 48 - 3 - 4 = 41 Therefore, P(black) = 41/48. (c) Let the required number be n. After...

分類：科學及數學 > 數學 2020年09月13日

6. ### Maths problem: how to do (b), thanks.?

...they have exactly the same total profit, which is quite impossible) Thus, l don 't agree with Emily's claim. ~~~~~~~~~~~~~~~~~~~~~~~ The End...

分類：科學及數學 > 數學 2020年08月19日

7. ### Maths problem: how to do, thanks?

(b) Total length = (2.6 x 10⁵) x (4.5 x 10⁻⁷) = (2.6 x 4.5) x (10⁵ x 10⁻⁷)= 11.7 x 10⁻² = 1.17 x 10⁻¹ m

分類：科學及數學 > 數學 2020年08月05日

8. ### Maths problem: I don 't know how to do (b), thanks.?

(a)  2πr(60⁰/360⁰)+2r = 5π+30 πr/3+2r = 5π+30 r(π+6)/3 = 5(π+6) ∴ r = 15 (b) area of △AOB = (1/2) r*r sin60⁰ - - - -(#) 　　　　　　　= (1/2)15² (√3/2) 　　　　　　　= 225√3/4 area of sector = πr²(60⁰/360⁰) = π*15²/6 = 225π/6...

分類：科學及數學 > 數學 2020年07月23日

9. ### Maths problem: I need help, I don 't know how to determine constant or not constant, thanks.?

x,y,z are VARIABLES, 每一個會因其他兩個的"轉變"而"改變". Given that: y α x, y α 1/√z  Connecting the relationship of x,y,z, we have: y = kx/√z,where k -- a constant(不會變的數字)  　...^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^... a) y/x = constant or not ? =================== y...

分類：科學及數學 > 數學 2020年04月19日

10. ### Maths problem, I don 't know how to calculate the answer is 14 cm. Thanks?

The internal radius is 11cm The external radius is 14cm (answer) The hemispherical volume should be V = 2/3 x π x (14³ - 11³) = 2959.38028 {The net space volume between two hemispherical volumes) So either you copy the question incorrectly as...

分類：科學及數學 > 數學 2019年02月15日