Question

Сделать всё 14, 20 балов!

Answer 1

Объяснение:

$a)\; \; (a+b)^2=a^2+\underline {2ab}+b^2\; \; \to \; \; (\star )=2ab\\\\\\b)\; \; (b+10)^2=b^2+20b+\underlien {100}\; \; \to \; \; (\star )=100$

в)   $b^2-20b+\underbrace {\star }_{100}=(\underbrace {\star }_{b}-10)^2$

$b^2-20b+100=(b-10)^2$

г)   $\underbrace {\star }_{9p^2}-42pq+49q^2=(3p-\underbrace {\star }_{7q})^2$

$9p^2-42pq+49q^2=(3p-7q)^2$

д)   $25a^2+\; \underbrace {\star }_{2\cdot 5a\cdot \frac{1}{2}b}\; +\frac{1}{4}b^2=(\underbrace {\star }_{5a}+\frac{1}{2}b)^2$

$25a^2+5ab+\frac{1}{4}b^2=(5a+\frac{1}{2}b)^2$

е)   $\star \; -70pg+\, \star \, =(7p-\, \star \, )^2$

$\star \, -2\cdot 35pq+\, \star \, =(7p-\, \star )^2\\\\\underbrace {\star }_{(7p)^2}-2\cdot 5q\cdot 7p+\underbrace {\star }_{(5q)^2}=(7p-\underbrace {\star }_{5q})^2\\\\49p^2-70pq+25q^2=(7p-5q)^2$