Răspuns:
Explicație pas cu pas:
[tex]\frac{1}{4}x^{2}-3x+9=(\frac{1}{2}x)^{2}-2*(\frac{1}{2}x*3+3^{2}=(\frac{1}{2}*x-3)^{2};\\x^{2}+x+\frac{1}{4}= x^{2}+2*x*\frac{1}{2} +(\frac{1}{2})^{2}=(x+\frac{1}{2})^{2};\\4x^{2}-49=(2x)^{2}-7^{2}=(2x-7)(2x+7);\\5x^{2}-3=(\sqrt{5}x)^{2}-(\sqrt{3})^{2}=( \sqrt{5}x-\sqrt{3})( \sqrt{5}x+\sqrt{3})[/tex]