约分:3m^2n^3[x^-1]/9mn^2[1-x] 若x^2+3x+1=0 求x^2+1/x^2的值· 已知1/x-1/y=3求5x+xy-5y/x-xy-y的值
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![约分:3m^2n^3[x^-1]/9mn^2[1-x] 若x^2+3x+1=0 求x^2+1/x^2的值· 已知1/x-1/y=3求5x+xy-5y/x-xy-y的值](/uploads/image/z/12665965-13-5.jpg?t=%E7%BA%A6%E5%88%86%3A3m%5E2n%5E3%5Bx%5E-1%5D%2F9mn%5E2%5B1-x%5D+%E8%8B%A5x%5E2%2B3x%2B1%3D0+%E6%B1%82x%5E2%2B1%2Fx%5E2%E7%9A%84%E5%80%BC%C2%B7+%E5%B7%B2%E7%9F%A51%2Fx-1%2Fy%3D3%E6%B1%825x%2Bxy-5y%2Fx-xy-y%E7%9A%84%E5%80%BC)
约分:3m^2n^3[x^-1]/9mn^2[1-x] 若x^2+3x+1=0 求x^2+1/x^2的值· 已知1/x-1/y=3求5x+xy-5y/x-xy-y的值
约分:3m^2n^3[x^-1]/9mn^2[1-x] 若x^2+3x+1=0 求x^2+1/x^2的值· 已知1/x-1/y=3求5x+xy-5y/x-xy-y的值
约分:3m^2n^3[x^-1]/9mn^2[1-x] 若x^2+3x+1=0 求x^2+1/x^2的值· 已知1/x-1/y=3求5x+xy-5y/x-xy-y的值
1.原式=mn^(3/x-2+2x)/3
2.x^2+3x+1=0
解得x=-(√5+3)/2或=(√5-3)/2
x^2+1/x^2
=(x+1/x)^2-2
代入x值
=7
3.1/x-1/y=3
各项同乘xy
即y-x=3xy
5x+xy-5y/x-xy-y
=-5(y-x)+xy/-(y-x)-xy
=-3xy+xy/-3xy-xy
=-2xy/-4xy
=1/2
第一题
=mn^(3/x-2+2x)/3
第二题
若x^2+3x+1=0 求x^2+1/x^2的值
因为x1=(√5-3)/2,x2=(-√5+3)/2
1/x1=-(√5+3)/2;1/x2=(√5+3)/2
因为 x^2+1/x^2=(x+1/x)^2-2
=7
第三题
又没有打错啊