Odpowiedź :
2x^2+9x-5=(2x-1)^2
4x^2+9x-5=2x^2+1^2-2*1*2x
4x^2+9x-5=4x^2+1-4x
4x^2+9x-4x^2+4x=1+5
13x=6/13
x=6/13
4x^2+9x-5=2x^2+1^2-2*1*2x
4x^2+9x-5=4x^2+1-4x
4x^2+9x-4x^2+4x=1+5
13x=6/13
x=6/13