鍾倩怡

1.If 4x^2+12x+k=0 has equal roots,
(a)Find the value of k
(b)Find the roots.
2.(a)Solve the quadratic equation 0=x^2+kx+2.
(b)Find the value of k.
3. A hawker bought a certain number of apples for $900, and sold them at 3 for $10. By so doing, he earned as much as he paid for 300 apples. How many apples did he buy?
4.The daily profit, P in dollars, of a company is given by P=-2x^2+120x-800, where x is the number of articles produced per day.
(a)Find x so that the daily profit is a maximum.
(b)What is the maximum daily profit?
5. Let f(x)=6x64-17x^3-8x62+13x+6
(a) find f(1)
(b) find f(3)
(c) factorize f(x)
6.Let f(x)=x^964-2x+3
(a)Find the remainder when f(x) is divided by x-1.
(b)Find the remainder when 8^964-13 is divided by 7.
(c)Find the remainder when 8^964 is divided by 7.

[ 本帖最後由 鍾倩怡 於 2006-11-10 11:04 PM 編輯 ]

Eraser

1.If 4x^2+12x+k=0 has equal roots,
(a)Find the value of k
     If 4x^2+12x+k=0 has equal roots
     b^2-4ac =0
     a=4, b=12, c=k
     (12)^2 - 4(4)k =0
     144-16k=0
      144=16k
       k=9
(b)Find the roots.
     4x^2 + 12x + k =0
     4x^2 + 12x + 9 =0
         (2x+3)(2x+3)=0
                       2x+3=0
                            2x=-3
                              x=-3/2