Toán Lớp 6: tim so nguyen x de :
C= 3x^2 – 2 / 3x^2 +1
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Toán Lớp 6: tim so nguyen x de :
C= 3x^2 – 2 / 3x^2 +1
Comments ( 1 )
C=(3x²-2)/(3x²+1)=(3x²+1-3)/(3x²+1)=3/(3x²+1)
Để C∈ZZ=>3/(3x²+1)∈ZZ
=>3\vdots 3x²+1
=>3x²+1∈Ư(3)={+1;+-3}
=>3x²∈Ư(3)={-2;0;2;-4}
Mà 3x²>=0
=>3x²∈{2;0}
=>x²∈{2/3(KTM);0}
=>x=0