va rog am nevoie repede:
calculati:
a) (x-7) (x+3)=
b) (2x+1) (x-9)=
c) (x²+1) (x²-5)=
d) (a+b) (a-2b)=
e) (x-3) (x²+3x+9)=
f) (x+5) (x2-5x-25)=
​