Toán Lớp 8: (2x – 1)^2 + (x + 3)^2 – 5(x + 7)(x – 7) = 0
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Toán Lớp 8: (2x – 1)^2 + (x + 3)^2 – 5(x + 7)(x – 7) = 0
Comments ( 2 )
<=> 4x^2-4x+1+x^2+6x+9-5(x^2-49)=0
<=> 4x^2-4x+1+x^2+6x+9-5x^2+245=0
<=> 2x+255=0
<=> 2x=-255
<=> x=-127,5
Vậy S ={-127,5}