Question

погите плиииииз дам 90 баллов!!!!​

Answer 1

Объяснение:

$\underbrace {g^2+5z+9z^2}_{a^2+2ab+b^2}=\underbrace{g^2}_{a^2}+\underbrace {2\cdot \frac{1}{2}\cdot 5z}_{2ab}+\underbrace{(3z)^2}_{b^2,\, b=3z}=g^2+\underbrace{2\cdot \frac{1}{2}\cdot 3z\cdot \frac{5z}{3z}}_{2ab}+\underbrace {(3z)^2}_{b=3z}=\\\\\\\star \ \ 2ab=2\cdot \frac{1}{2}\cdot 3z\cdot \frac{5z}{3z}=2\cdot \underbrace {3z}_{b}\cdot \underbrace {\frac{5z}{2\cdot 3z}}_{a}=2\cdot \underbrace {3z}_{b}\cdot \underbrace {\frac{5}{6}}_{a}\ \ \ \star$

$=\Big(\frac{5}{6}\Big)^2+2\cdot \frac{5}{6}\cdot 3z+(3z)^2=\dfrac{25}{36}+5z+9z^2=\Big(\, \dfrac{5}{6}+3z\Big)^2\\\\\\g^2=\dfrac{25}{36}$