(x-1)(x-2)(x-3)(x-4) ≥25(x-1)(x-4)(x-2)(x-3)-25≥0(x²-5x+4)(x²-5x+6)-25≥0(x²-5x+4)²+2(x²-5x+4)-25≥0(x²-5x+4+1)²≥26x²-5x+5≥√26x²-5x+5-√26≥0x≥(5+√(...