Toán Lớp 8: Tìm x
a)(x+6)^2-x.(x-4)-30=0
b) x(x-11)+3x-33=0
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Toán Lớp 8: Tìm x
a)(x+6)^2-x.(x-4)-30=0
b) x(x-11)+3x-33=0
Comments ( 2 )
(x+6)^2-x.(x-4)-30=0
<=>x^2+2.x.6+6^2-x^2+4x-30=0
<=>x^2+12x+36-x^2+4x-30=0
<=>16x+6=0
<=>16x=-6
<=>x=-3/8
Vậy x=-3/8
b)
x.(x-11)+3x-33=0
<=>x.(x-11)+3.(x-11)=0
<=>(x-11).(x+3)=0
<=>[(x-11=0),(x+3=0):}
<=>[(x=11),(x=-3):}
Vậy x\in{-3;11}