1 numar langa litera inseamna deinmultit
.a=8n
b=8m
ab=1280=64mn
mn=1280:64=20
mn=20=1*20=4*5=5*4=20*1
( m, n) ∈{(1,20);(4,5);(5,4);(20,1)}
atunci a si b vor fi de 8 ori mai mari
(a,b) ∈ {(8,160); (32,40); (40,32);(160;8)}
2. [2+2x(x+2)]=36:2=18
2x(x+2)=18-2=16
x(x+2)=16:2=8
x(x+2)=8
x²+2x-8=0
x²+4x-2x-8=0
x(x+4)-2(x+4)=0
(x-2)(x+4)=0
x-2=0⇒x=2
x+4=0⇒x=-4
x∈{-4;2}
