Tìm x , biết: (a) x − 1/6 = x − 5/7 ; (b) ( x − 1 ) ( 3 − 2 x ) + ( 2 x − 1 ) ( x + 3 ) = 4 .
Giải thích
a) \(\frac{{x - 1}}{6} = \frac{{x - 5}}{7}\)
\(7.\left( {x - 1} \right) = 6.\left( {x - 5} \right)\)
\(7x - 7 = 6x - 30\)
\(x = 37\)
Vậy \(x = 37\).
b) \[\left( {x - 1} \right)\left( {3 - 2x} \right) + \left( {2x - 1} \right)\left( {x + 3} \right) = 4\]
\(3x - 2{x^2} - 3 + 2x + 2{x^2} + 6x - x - 3 = 4\)
\[10x = 10\]
\(x = 1\).
Vậy \(x = 1\).