[toán 8] tìm x , biết

N

nguyenbahiep1

a)

[TEX] 3x(12x-4)-9x(4x-3)=30 \\ 36x^2 -12x -36x^2 + 27x = 30 \\ 15x = 30 \\ x = 2[/TEX]


b)

[TEX]x(5-2x)+2x(x-1)=15 \\ 5x -2x^2 +2x^2 -2x =15 \\ 3x = 15 \\ x =5[/TEX]
 
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