(t2+t-1)(t2+t+2)=4解题过程 一元二次方程

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(t2+t-1)(t2+t+2)=4解题过程 一元二次方程
(t2+t-1)(t2+t+2)=4解题过程 一元二次方程

(t2+t-1)(t2+t+2)=4解题过程 一元二次方程
令u=t^2+t+2
那么原式变为
u^2-3u=4
所以u=4或u=-1
u=4时,t^2+t+2=4
所以t=1或t=-2
u=-1时,t^2+t+2=-1
得(t+1/2)^2+3/4=0无解
所以t=1或t=-2

设(t+1)3=x,y=2+t+t2,则
原式=[(4+2t+2t2)-3(1+3t+3t2+t3)],
=[(2+t+t2)-(1+3t+3t2+t3)]-[(t+1)3]2,
=(2y-3x)(y-x)-x2,
=2x2-5xy+2y2,
=(2x-y)(x-2y),
=[2(t3+3t2+3t+1)-(t2+t+2)][(t3+3t2+3t+1...

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设(t+1)3=x,y=2+t+t2,则
原式=[(4+2t+2t2)-3(1+3t+3t2+t3)],
=[(2+t+t2)-(1+3t+3t2+t3)]-[(t+1)3]2,
=(2y-3x)(y-x)-x2,
=2x2-5xy+2y2,
=(2x-y)(x-2y),
=[2(t3+3t2+3t+1)-(t2+t+2)][(t3+3t2+3t+1)-2(t2+t+2)],
=(2t3+5t2+5t)(t3+t2+t-3),
=t(2t2+5t+5)(t-1)(2t2+2t+3).
故答案为:t(2t2+5t+5)(t-1)(2t2+2t+3).

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