Raspuns:
[tex]\frac{1+12ax+36a^2x^2}{9a^2}[/tex]
Explicație pas cu pas:
Folosim formula: (a+b)²=a²+2xaxb+b²
notam cu a=1/3a si cu b=2x si atunci trecem la calcul
[tex]\displaystyle(\frac{1}{3a} +2x)^{2} =(\frac{1}{3a} )^2+2\times (\frac{1}{3a} )\times 2x+(2x)^2=\frac{1}{ 9a^2} +\frac{4x}{3a} +4x^2=\frac{1}{ 9a^2}+\frac{4x\times 3a}{9a^2} +\frac{4x^2\times 9a^2}{9a^2} =\frac{1+12ax+36a^2x^2}{9a^2}[/tex]
