Tìm giá trị của x , biết: (a) 3 x − 7/8 = 5/2 ; (b) ( 4 x^4 − 3 x^3 + x^2 ) : ( − x^2 ) + 4 ( x − 1 )^2 = 0 .

a) \(\frac{{3x - 7}}{8} = \frac{5}{2}\)

\(2.\left( {3x - 7} \right) = 8.5\)

\(6x - 14 = 40\)

\(6x = 54\)

\(x = 9\)

Vậy \(x = 9\).

b) \(\left( {4{x^4} - 3{x^3} + {x^2}} \right):\left( { - {x^2}} \right) + 4{\left( {x - 1} \right)^2} = 0\)

\(\left( {4{x^4}} \right):\left( { - {x^2}} \right) - \left( {3{x^3}} \right):\left( { - {x^2}} \right) + \left( {{x^2}} \right):\left( { - {x^2}} \right) + 4\left( {x - 1} \right)\left( {x - 1} \right) = 0\)

\( - 4{x^2} + 3x - 1 + 4\left( {{x^2} - x - x + 1} \right) = 0\)

\( - 4{x^2} + 3x - 1 + 4{x^2} - 8x + 4 = 0\)

\( - 5x + 3 = 0\)

\(x = \frac{3}{5}\)

Vậy \(x = \frac{3}{5}\).