Question

Doar rezultatele !!!
1)Descompuneti in factori :
a)5a-5b
b)(3x-4)•(x+7)-(x+7)•(2x-5)
c)4x^2-49
d)9(x+3)^2-4x^2
e)5x^2-10x+5
f)a^2+2a+1-b^2

2) a)Daca a-b=1,calculati a^2+a-2ab+b^2-b
b) Daca a+b=2,calculati a^2+b^2+2a+2b+2ab

Answer 1

1)Descompuneti in factori :
a)5a-5b =5(a-b)
b)(3x-4)•(x+7)-(x+7)•(2x-5) =(x+7)(3x-4-2x+5)=(x+7)(x+1)
c)4x^2-49=(2x+7)(2x-7)
d)9(x+3)^2-4x^2=[3(x+3)+2x][3(x+3)-2x]=(3x+9+2x)(3x+9-2x)=(5x+9)(x+9)
e)5x^2-10x+5 =5(x-1)^2
f)a^2+2a+1-b^2 =(a+1)^2-b^2=(a+1+b)(a+1-b)

2) a)Daca a-b=1,calculati a^2+a-2ab+b^2-b =(a-b)^2+(a-b)=1+1=2
b) Daca a+b=2,calculati a^2+b^2+2a+2b+2ab =(a+b)^2+2(a+b)=2^2+2*2=4+4=8