{5x-3(20-x)≥70,5x-3(20-x)≤90

{5x-3(20-x)≥70,5x-3(20-x)≤90 4x-3x(20-x)=5x-7x(20-x) 4x-3x(20-x)=5x-7x(20-x)的解法 用递归法求y=x-(x*x*x/3!)+(x*x*x*x*x/5!)-(x*x*x*x*x*x*x/7!)+. 3≤|8-x| |x+1|>2-x |x+3|7|x+1| x^2-6|x|+9>0 |x-1|+|x+2|≥5 x+2/x+1-x+3/x+2-x+4/x+3+x+5/x+4 x^5+x^4 = (x^3-x)(x^2+x+1)+x^2+x X+1-3X=5X+10 6-3X=5X-20 x/x-3-5x/x^2-x-6计算 4x^2-20x+18/x^2-5x+4≥3 |X-1|+|X-2|+|X-3|+|X-4|+|X-5|+|X-6|+|X-7|+|X-8|+|X-9|+|X-10| 5x-20*5=3x x=?