解方程组1.x^2+9≤6x
x^2-6x+9=0
(x-3)^2=0
x=3,x=-3
2.(7-x)(5+3x)≥0
(3x+5)(x-7)《0
-5/3《x《7
3.12x^2-11x+2大于0
12x^2-11x-2>0
x>(11+√217)/4
x
解方程组1.x^2+9≤6x
x^2-6x+9=0
(x-3)^2=0
x=3,x=-3
2.(7-x)(5+3x)≥0
(3x+5)(x-7)《0
-5/3《x《7
3.12x^2-11x+2大于0
12x^2-11x-2>0
x>(11+√217)/4
x