Toán Lớp 8: Bài 1: Tìm x
A) 7x(x-3) – (3-x)(5x+1) =0
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Toán Lớp 8: Bài 1: Tìm x
A) 7x(x-3) – (3-x)(5x+1) =0
Comments ( 2 )
a)
7x.(x-3)-(3-x).(5x+1)=0
<=>7x.(x-3)+(x-3).(5x+1)=0
<=>(x-3).(7x+5x+1)=0
<=>(x-3).(12x+1)=0
<=>[(x-3=0),(12x+1=0):}
<=>[(x=3),(12x=-1):}
<=>[(x=3),(x=-1/12):}
Vậy x\in{3;-1/12}