Toán Lớp 8: Tìm x
( 2x + 1 )^2 – 4 ( x – 1 )( x + 1 ) = 9
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Toán Lớp 8: Tìm x
( 2x + 1 )^2 – 4 ( x – 1 )( x + 1 ) = 9
Comments ( 2 )
<=> (2x+1)^2 -(2x+4)^2=0
<=> (2x+1+2x+4)(2x+1-2x-4)=9
<=> (4x+5).(-3)=9
<=> 4x+5=-3
<=> x=-2
Vậy x=-2