80/X + 220/(X+15)=6大神们帮帮忙
X/2-5X+11/6=1+2X-4/3大神们帮帮忙
解方程组2/(X+3)+6/(X-9)=1/(X-3)大神们帮帮忙
2(x+y)-3(x-y) =1 6(x+y)+7(x-y)=51大神们帮帮忙
f(x+1)=x^2+2x+5,求f(x)大神们帮帮忙
求导y=(x+1)(x+2)(x+3)(x+4)的导数大神们帮帮忙
(2x-3)(2x-3)-5(2x-3)+6=0大神们帮帮忙
4x减x等于6x等多少解方程大神们帮帮忙
x+3x=2*(x+300)怎么解大神们帮帮忙
求y=1/x-3 +x (x>3)的最小值大神们帮帮忙
4x?+165x+875=0,x等于多少大神们帮帮忙
若x-x的负一次方=3,求x/x+x+1的值大神们帮帮忙
x 平方+8x+12怎么做?大神们帮帮忙