Tìm số nguyên x biết. (a) 17 − 3 x = 32 . (b) 2. ( x + 7 ) − 14 = 108 .
Giải thích
a) \(17 - 3x = 32\)
\(3x = 17 - 32\)
\(3x = - 15\)
\(x = \left( { - 15} \right):3\)
\(x = - 5\)
Vậy \(x = - 5\).
b) \(2.\left( {x + 7} \right) - 14 = 108\)
\(2.\left( {x + 7} \right) = 108 + 14\)
\(2.\left( {x + 7} \right) = 122\)
\(x + 7 = 122:2\)
\(x + 7 = 61\)
\(x = 61 - 7\)
\(x = 54\)
Vậy \(x = 54\).
d) \(\left( {160 - 41} \right) - {5.3^{2x - 1}} = - 16\)
\(119 - {5.3^{2x - 1}} = - 16\)
\({5.3^{2x - 1}} = 119 - \left( { - 16} \right)\)
\({5.3^{2x - 1}} = 135\)
\(\begin{array}{l}{3^{2x - 1}} = 27\\{3^{2x - 1}} = {3^3}\end{array}\)
Suy ra \(2x - 1 = 3\)
\(2x = 3 + 1\)
\(2x = 4\)
\(x = 2\)
Vậy \(x = 2\).