Toán Lớp 8: 3x^2 + 4.(x-1).(x+1) – 7x.(x-1) = x + 12
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Toán Lớp 8: 3x^2 + 4.(x-1).(x+1) – 7x.(x-1) = x + 12
Comments ( 2 )
<=>3x^2+4.(x^2-1^2)-7x^2+7x=x+12
<=>3x^2+4.x^2-4-7x^2+7x-x-12=0
<=>(3x^2+4x^2-7x^2)+(7x-x)+(-12-4)=0
<=>6x-16=0
<=>6x=0+16
<=>6x=16
<=>x=16/6
<=>x=8/3
Vậy phương trình có nghiệm S={8/3}