1.
a) (2x + 1)3 =343
\(\Leftrightarrow\left(2x+1\right)^3=7^3.\)
\(\Leftrightarrow2x+1=7\Rightarrow x=3\)
b) 720 [ 41 (2x - 5)] = 23 . 5
\(\Leftrightarrow720\left[41\left(2x-5\right)\right]=40\)
\(\Leftrightarrow41\left(2x-5\right)=\frac{40}{720}=\frac{1}{18}\)
\(\Leftrightarrow2x-5=\frac{1}{738}\)
\(\Leftrightarrow2x=\frac{3691}{738}\Leftrightarrow x=\frac{3691}{1476}\)