Question

-2X²-X³-6X=4,求X?

Answer 1

跟你商量一下,把原题等号右边改成5

-2X^2-X^3-6X=5

X(X^2+2X+6)= -5

X[(X+1)^2+5]+5=0

X(X+1)^2+5x+5=0

X(X+1)^2+5(x+1)=0

(X+1)[X(X+1)+5]=0

(X+1)[(X+1/2)^2+19/4]=0

(X+1/2)^2+19/4=0 无解,所以 X+1=0,X= -1

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