a) (x-3)²+x(x+9)=
x²-6x+9+x²+9x= 2x²+3x+9
b) (2a+5)²-5(4a+5)=
4a²+20a+25-20a-25= 4a²
c) 9b(b-1)-(3b+2)²=
9b²-9b-(9b²+12b+4)=
9b²-9b-9b²-12b-4= -21b-4
d) (b-4)²+(b-1)(2-b)=
b²-8b+16+2b-b²-2b+b= -7b+16
e) (a+3)(5-a)-(a-1)²=
5a-a²+15-3a-(a²-2a+1)=
5a-a²+15-3a-a²+2a-1= 4a-2a²+14
f) (5+2y)(y-3)-(5-2y)²=
5y-15+2y²-6y-(25-20y+4y²)=
5y-15+2y²-6y-25+20y-4y²= -2y²+19y-40
Reține:
(a+b)(a-b)=(a)²-(b)²
(a+b)²=(a)²+2•(a)•(b)+(b)²
(a+b+c)²=(a)²+(b)²+(c)²+2•(a)•(b)+2•(a)•(c)+2•(b)•(c)
(a+b)³=(a)³+(b)³+3•(a)²•(b)+3•(a)•(b)²
sper că te-am ajutat
