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Laura68
a fost răspuns

Descompuneti expresia: (4x-1)^2-81=?

Răspuns :

 (4x-1)²-81=
=(4x-1-9)(4x-1+9)=
=(4x-10)(4x+8)=
=8(2x-5)(x+2)
(4x-1)^2-81= (4x-1)^2-9^2= (este formula (a+b)(a-b)=a^2-b^2) =(4x-1-9)(4x-1+9)= =(4x-10)(4x+8)= =2(2x+5)*4(x+2)= =8(2x+5)(x+2). Bafta!