f.4 maths.

2014-03-01 11:00 pm
(1) find the quotient and remainder when [(3x^3 +2x -3 )-(x^3-4x^2+4)]
÷ (x^2 -3x + 5)


(2) When 3x^3 - 5x^2 + x +p is divided by x^2-x-6 , the quotient and remainder are 3x-2 and qx-18 respectively. Find the values of p and q.

回答 (1)

2014-03-01 11:25 pm
✔ 最佳答案
(1) find the quotient and remainder when [(3x^3 +2x -3 )-(x^3-4x^2+4)]
÷ (x^2 -3x + 5)

[(3x^3 +2x -3 )-(x^3-4x^2+4)] ÷ (x^2 -3x + 5)
=(2x³+6x²+2x-7) ÷ (x² -3x + 5)

       2x + 12
       ______
  (x² -3x + 5) ) 2x³+6x²+2x-7
        2x³-6x²+10x
       ___________
         12x²-8x-7
         12x²-36x+60
         __________
           28x-67

quotient = 2x + 12

remainder = 28x-67

(2) When 3x^3 - 5x^2 + x +p is divided by x^2-x-6 , the quotient and remainder are 3x-2 and qx-18 respectively. Find the values of p and q.

       3x - 2
       ______
  (x² -x - 6 ) ) 3x³-5x²+x+p
       3x³-3x²-18x
       ___________
         -2x²-19x+p
         -2x²+2x+12
         __________
           17x+(p-12)

17x+(p-12) = qx-18

q = 17
p=-6



2014-03-01 15:40:49 補充:
       3x - 2
       ______
  (x² -x - 6 ) ) 3x³-5x²+x+p
       3x³-3x²-18x
       ___________
         -2x²+19x+p    [ 19x 錯± ]
         -2x²+2x+12
         __________
           17x+(p-12)

2014-03-01 17:39:54 補充:
又計錯!

(1) find the quotient and remainder when [(3x^3 +2x -3 )-(x^3-4x^2+4)]
÷ (x^2 -3x + 5)

[(3x^3 +2x -3 )-(x^3-4x^2+4)] ÷ (x^2 -3x + 5)
=(2x³+4x²+2x-7) ÷ (x² -3x + 5)


       

2014-03-01 17:40:40 補充:
         2x+10
       ──────────────
x2-3x+5)2x3+4x2+ 2x-7
       )2x3-6x2+10x
       )─────────────
       )10x2- 8x- 7
       )10x2-30x+50
       )─────────────
       )22x-57
quotient=2x+10
remainder=22x-57

2014-03-01 17:41:19 補充:
多謝 螞蟻雄兵 ( 知識長 ) 更正


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