(180-x) 2 - 20 =90-x
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(20-2x)(20-2x)x>400400-80x+4x²>400x²-20x>0x(x-20)>0x<0x>20
3分之1(180-x)-20=90-x两边都乘以3180-x-60=270-3x120-x=270-3x3x-x=270-1202x=150x=75
180-x=2(90-x)+20180-x=180-2x+20x=20再问:具体过程再答:首先打开括号180-x=180-2x+20左右两边都加2x-180变为:x=20
30%X-30%X-[(X-30%X)×20%-2]-30%X=280-(0.7X×0.2-2)-0.3X=28-0.14X+2-0.3X=280.44X=-26X=-59又11分之1
90/(x-90)=(2x-50)/(x+50)(2x-50)(x-90)=90(x+50)2x^2-230x+4500=90x+45002x^2-230x-90x+4500-4500=02x^2-3
(X-X*20%-18)-(X-X*20%-18)*10%=X*1/2-3则(X*80%-18)*90%=X*1/2-372%*X-16.2=X*1/2-322%*X=13.2X=60
(x-2)*180/x*x=360x-2=360/180X=4
20+0.8x=x-14x-0.8x=20+140.2x=34x=170112-4x=2x(80-4x)112-4x=160-8x8x-4x=160-1124x=48x=12
90-X=(180-X)/3+2090-X=180/3-X/3+2090-X=60-X/3+2010=2x/3x=15
3x+x/3=180+306x+x=210*37x=630x=90
60X+15X+10X+6X=12091X=120X=120/91
x/2+x/6+x/12+x/20+x/30+x/42=136x/42=1x=7/6
x^2+3x=6x^2=-3x+6x^3=x*x^2=x(-3x+6)=-3x^2+6x所以x^3+x^2+2x+20=-3x^2+6x+x^2+2x+20=-2x^2+8x+20=-2(x^2-4x
x/2+2+(x/2-2)/2-2=x-20x/2+2+x/4-1-2=x-20两边同时乘4,得2x+x-4=4x-80把3x移至左边-4+80=4x-3x即x=76
两边乘3270-3x=180-x-603x-x=270-180+602x=150x=150÷2x=75
原方程化为:(1/2+1/6+1/12+1/20+1/30+1/42)x=6【(1-1/2)+(1/2-1/3)+(1/3-1/4)+(1/4-1/5)+(1/5-1/6)+(1/6-1/7)】x=6
你懒惰了,通分得:50x=300x=6
cosx=±√[1-(sinx)^2]=±1/2∵90〈X〈180度∴cosx=-1/2tanx=sinx/cosx=-√3cotx=cosx/sinx=-√3/3secx=1/cosx=-2cscx
50x/60=5x=6
90x-90×180=60x+60*18030x=180(60+90)x=6*150=900