Tìm giá trị của x biết (a) − 2 x − 37 = − 19 . (b) ( 4 x + 16 )^3 + 17 = ( − 3 )^4 .
Giải thích
a) \( - 2x - 37 = - 19\)
\( - 2x = - 19 + 37\)
\( - 2x = 18\)
\(x = - 9\).
Vậy \(x = - 9\).
b) \({\left( {4x + 16} \right)^3} + 17 = {\left( { - 3} \right)^4}\)
\({\left( {4x + 16} \right)^3} = 81 - 17\)
\({\left( {4x + 16} \right)^3} = 64 = {8^3}\)
\(4x + 16 = 8\)
\(4x = 8 - 16\)
\(4x = - 8\)
\(x = - 2\)
Vậy \(x = - 2\).
c) \(x - \frac{5}{6} = \frac{7}{{12}} + \frac{{ - 1}}{4}\)
\(x - \frac{5}{6} = \frac{7}{{12}} + \frac{{ - 3}}{{12}}\)
\(x - \frac{5}{6} = \frac{4}{{12}}\)
\(x = \frac{4}{{12}} + \frac{5}{6}\)
\(x = \frac{2}{6} + \frac{5}{6}\)
\(x = \frac{7}{6}\)
Vậy \(x = \frac{7}{6}\).