k為何整數時,方程(k²-1)x²-6(3k-1)x+72=0有兩個不相等的正整數跟?

k為何整數時,方程(k²-1)x²-6(3k-1)x+72=0有兩個不相等的正整數跟?

[(k+1)x-12][(k-1)x-6]=0二次項係數不等於0 得 k不等於1,-1; Δ=36(3k-1)^2-4*72*(k^2-1)=36(k-3)^2>=0 解得根為x1=12/(k+1),x2=6/(k-1) 所以 k+1=1,2,3,4,6,12,即k=0,1,2,3,5,11; k-1=1,2,3,6,即 k=2,3,4,7; 取...