Răspuns :
c) 4x²-49=(2x-7)(2x+7)
d) 9(x+3)²-4x²=[3(x+3)-2x][3(x+3)+2x]=(3x+9-2x)(3x+9+2x)=(x+9)(5x+9)
d) 9(x+3)²-4x²=[3(x+3)-2x][3(x+3)+2x]=(3x+9-2x)(3x+9+2x)=(x+9)(5x+9)
4x^-49=(2x-7)(2x+7)
9(x+3)^2-4x^2=
9x^2+54x+81−4x^2=
5x^2+54x+81=
Il scrii pe 54x ca 9x+45x
5x^2+9x+45x+81=
x(5x+9)+9(5x+9)=
(5x+9)(x+9)
9(x+3)^2-4x^2=
9x^2+54x+81−4x^2=
5x^2+54x+81=
Il scrii pe 54x ca 9x+45x
5x^2+9x+45x+81=
x(5x+9)+9(5x+9)=
(5x+9)(x+9)