解方程:(X-50)[200+2(70-X)]=4500 (30-2X)(20-2X)=(1-3/8)×30×20 (-1/10X+30)(X-60)=1340

(X-50)[200+2(70-X)]=4500 (X-50)[340-2X]=4500-2X^2+440X-1700=4500X^2-220X+3100=0(X-110)^2=8000X=±40√5+110(30-2X)(20-2X)=(1-3/8)×30×20600-100X+4X^2=3754X^2-100X+225=04(X-12.5)^2=625-225X=12.5±10=22...还有4题。。W=(50-1/10X)(180+X-20)求W最大值 Y=(100+X)(100-1/2X)求Y的最大值(X-30)[600-10(X-40)]=10004X的平方+(100-2X)(80-2X)=5200x谢谢！！！！W=(50-1/10X)(180+X-20)=8000+34X-0.1X^2=-0.1(X-170)^2+10890Wmax=10890Y=(100+X)(100-1/2X)=10000+50X-0.5X^2=-0.5(X-50)^2+11250Ymax=11250(X-30)[600-10(X-40)]=1000(X-30)(100-X)=100X^2-130X+3100=0(X-65)^2=1125X=±15√5+65 4X^2+(100-2X)(80-2X)=52008X^2-360X+2800=0X^2-45X+350=0(X-10)(X-35)=0X=10 or 35max是什么东东？？我还没有学~~~最大值简写。。