Tinem cont de proprietatea progresiei geometrice care spune:
b²=ac
(x+7)²=(5-x)(3x+11)
x²+14x+49= 4x-3x²+55
4x²+10x-6=0 (s-a format o ecuatie de gradul doi)
4x²+10x-6=0 (impartim ecuatia prin 2)
2x²+5x-3=0
Δ=b²-4ac
Δ=25+2*3*4
Δ=25+24=49
√Δ=7
x1= -b+√Δ/ 2a
x1= -5+7 / 4=2/4 (simplificam prin doi)
x1= 1/2
x2= -b-√Δ /2a
x2= -5- 7/ 4 =>x2= -3
