a)
"V"=radical
(V3+7)(v3-7)=3-7x7=3-49=-46
b)
(2V2+1)(3V2-4)=2x3x2-4x2xV2+3V2-4=12-8V2+3V2-4=8-5V2
c)
(V12-5)(2V5+12)=2V(12x5)+12V12-5x2xV5-60=
=2V60+12V12-10V5-60=4V15+24V3-10V5-60=
=4V3 x(V5 +6) -10(V5 +6)=(6+V5)(4V3 -10)=2(6+V5)(2V3-5)
Pe acesta l-am putut scrie ca produs de factori primi.
d)
(5V7-V13)(5V7+V13)=(5x5x7-13)=175-13=162
