數學知識交流---解方程

2011-08-16 10:54 pm
解方程 (4x^2-19x-1)/(2x+3) = (9x-1)/(3x-4)

回答 (2)

2011-08-16 11:21 pm
✔ 最佳答案
解方程 (4x^2-19x-1)/(2x+3) = (9x-1)/(3x-4)
Sol
(4x^2-19x-1)/(2x+3) = (9x-1)/(3x-4)
(4x^2-19x-1)(3x-4)=(2x+3)(9x-1)
12x^3-73x^2+73x+4=18x^2+25x-3
12x^3-91x^2+48x+7=0
(12x^3-84x^2)+(-7x^2+49x)+(-x+7)=0
12x^2(x-7)-7x(x-7)-(x-7)=0
(12x^2-7x-1)(x-7)=0
x=7or x=(7+/-√97)/24


2011-08-16 11:39 pm
開頭第一步要寫明 2 個限制: x =/= -3/2 和 x =/= 4/3


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