1.X③-2X②-2X+1=02.(X②-5X+1)(X②-5X=9)+15=03.(X②+2)②+8X(X②+2)+15X②=0以上带圈的数字均为次数,如:X②就是X的平方.
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![1.X③-2X②-2X+1=02.(X②-5X+1)(X②-5X=9)+15=03.(X②+2)②+8X(X②+2)+15X②=0以上带圈的数字均为次数,如:X②就是X的平方.](/uploads/image/z/991832-32-2.jpg?t=1.X%E2%91%A2-2X%E2%91%A1-2X%2B1%3D02.%28X%E2%91%A1-5X%2B1%29%28X%E2%91%A1-5X%3D9%29%2B15%3D03.%28X%E2%91%A1%2B2%29%E2%91%A1%2B8X%28X%E2%91%A1%2B2%29%2B15X%E2%91%A1%3D0%E4%BB%A5%E4%B8%8A%E5%B8%A6%E5%9C%88%E7%9A%84%E6%95%B0%E5%AD%97%E5%9D%87%E4%B8%BA%E6%AC%A1%E6%95%B0%2C%E5%A6%82%EF%BC%9AX%E2%91%A1%E5%B0%B1%E6%98%AFX%E7%9A%84%E5%B9%B3%E6%96%B9.)
1.X③-2X②-2X+1=02.(X②-5X+1)(X②-5X=9)+15=03.(X②+2)②+8X(X②+2)+15X②=0以上带圈的数字均为次数,如:X②就是X的平方.
1.X③-2X②-2X+1=0
2.(X②-5X+1)(X②-5X=9)+15=0
3.(X②+2)②+8X(X②+2)+15X②=0
以上带圈的数字均为次数,如:X②就是X的平方.
1.X③-2X②-2X+1=02.(X②-5X+1)(X②-5X=9)+15=03.(X②+2)②+8X(X②+2)+15X②=0以上带圈的数字均为次数,如:X②就是X的平方.
1.
x^3+1-2x^2-2x=0.
<=>(x+1)(x^2-x+1)-2x(x+1)=0
<=>(x+1)(x^2-x+1-2x)=0
<=>(x+1)(x^2-3x+1)=0
<=>(x+1)[((x^2-2*3/2*x+9/4)-5/4]=0
<=>(x+1)[(x-3/2)^2-5/4]=0
=>x+1=0或x-3/2=√5/2或x-3/2=-√5/2.
<=>x=-1或x=(3+√5)/2或x=(3-√5)/2.
2.
(X②-5X+1)(X②-5X+9)+15=0
假令t=x^2-5x.
=>(t+1)(t+9)+15=0
<=>t^2+10t+24=0
<=>(t+4)(t+6)=0
=>t=-4或t=-6.
即:x^2-5x+4=0或x^2-5x+6=0
=>(x-4)(x-1)=0或(x-2)(x-3)=0.
=>x=1或x=2或x=3或x=4.
3.
.(X②+2)②+8X(X②+2)+15X②=0
假令x^2+2=t.
=>t^2+8x+15x^2=0
<=>(t+3x)(t+5x)=0
=>t=-3x或t=-5x.
即:x^2+2+3x=0或x^2+5x+2=0.
=>(x+1)(x+2)=0或x^2+2*5/2*x+25/4-17/4=0.
<=>x=-1或x=-2或(x+5/2)^2=17/4.
=>x=-(5+√17)/2或x=-2或x=-1或x=(√17-5)/2.
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