1

\(\frac{13}{25}+\frac14=\frac{77}{100}\)

\([2;3]\)

\(\dfrac{2^4\cdot9^5}{18^5}=\frac12\)

\(x=-\frac{39}{25}\)

\(R=\frac{225}{7{,}5^2}=4\ \text{Ом}\)

\((-\infty;-20]\cup[20;+\infty)\)

\(\frac{5(2\cdot0{,}7+4\cdot0{,}3)}2=6{,}5\) м