=> 9x+4==>(9x+4)*4=9x²-6x+1 36x+16-9x²+6x-1=0 -9x²+42x+15=0 |:3 -3x²+14x+5=0 Δ=14²-4*(-3)*5=196+60=256 √Δ=16. x2= b) am scris asa fiindca am simplificat prin 2 fractia 2x+2 supra 2 (se poate simplifica fiindca daca dai factor comun ai 2(x+1) totul supra 2) 5x+1=x²+2x+1=>x²+2x+1-5x-1=0 x²-3x=0 x(x-3)=0⇒ x=0 x-3=0⇒x=3
36x+16-9x²+6x-1=0
-9x²+42x+15=0 |:3
-3x²+14x+5=0
Δ=14²-4*(-3)*5=196+60=256
√Δ=16.
x2=
b)
5x+1=x²+2x+1=>x²+2x+1-5x-1=0
x²-3x=0
x(x-3)=0⇒ x=0
x-3=0⇒x=3