如果x2+x-1=0,求x3+2x2+3.

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如果x2+x-1=0,求x3+2x2+3.如果x2+x-1=0,求x3+2x2+3.如果x2+x-1=0,求x3+2x2+3.x3+2x2+3=x(x^2+x-1)+x^2+x+3=x*0+x^2+x

如果x2+x-1=0,求x3+2x2+3.
如果x2+x-1=0,求x3+2x2+3.

如果x2+x-1=0,求x3+2x2+3.
x3+2x2+3
=x(x^2+x-1)+x^2+x+3
=x*0+x^2+x-1+4
=0+0+4
=4

用^2 ^3 分别代表平方立方
X^2 + X - 1 = 0
所以
X^2 = 1 - X
X^3 = X^2 * X = (1-X)*X =X - X^2 = X - (1 - X) = 2X - 1
X^3 + 2X^2 + 3 = 2X-1 + 2*(1-X) + 3 = 1 + 3 = 4

因为x2+x-1=0
所以x^2+x=1
原式=x(x^2+x)+x^2+3
=(x^2+x)+3
=4

4
x2=1-x
代入
=x(x2)+2(x2)+3
=x(1-x)+2(1-x)+3
=x-(1-x)+2-2x+3
=4

x^2=1-x
x^3+2x^2+3
=x^2(x+2)+3
=(1-x)(x+2)+3
=-x^2-x+5
=-(1-x)-x+5
=4

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