解：（先有技巧地拆项，去括号，然后解三次方程）（2x-6)^2 - (2x+1)^2 = (9x^2 - 1) (3x+1)(4x-5)*(-7) = 27x^3 - 3x +9x^2 - 1-28x+32=27x^3 +9x^2 -3x-127x^3 +9x^2+25x -33=0解得x=0.72
