X/(X*X-1)+(X*X-1)/X=13/6
X=?
有幾組解?
要詳解喔
2007-09-01 15:54:49 · 2 個解答 · 發問者 林先生 3 in 科學 ➔ 數學
令 y = X/(X*X-1),則原式可以變成如下 :
y +(1/y) = 13/6
經計算可得y = 3/2 或 2/3
當y = 3/2時,代回y = X/(X*X-1)的式子
可解得x = (1 + √10) / 3 或 ( 1 - √10) / 3
當y = 2/3時,代回y = X/(X*X-1)的式子
可解得x = -1/2 或 2
所以總共有四組解......................(解答)
2007-09-01 16:25:12 · answer #1 · answered by 釋塵 7 · 0⤊ 0⤋
將原式通分後可得:(X^4-X^2+1)/(X^3-X)=13/6,用十字交乘法可得:6X^4-6X^2+6=13X^3-13X,
6X^4-13X^3-6X^2+13X+6=0,用綜合除法知X=2,X=-1/2,所以6X^4-13X^3-6X^2+13X+6=(X-2)(2X+1)(3X^2-2X-3), 3X^2-2X-3可用公式得到X=(1+-根號10)/3
2007-09-02 10:41:40 · answer #2 · answered by GONG 6 · 0⤊ 0⤋