解：?$(1)$?根據(jù)新運(yùn)算的定義，我們有
?$ (-2)*4 = (-2) × 4^2 + 2 × (-2) × 4 - 4$?
?$ = -32 - 16 - 4$?
?$ = -52$?
?$ (2)$?根據(jù)新運(yùn)算的定義，我們有
?$ (x - 1)*3 = (x - 1) × 3^2 + 2 × (x - 1) × 3 - 3$?
?$ = 9(x - 1) + 6(x - 1) - 3$?
?$ = 9x - 9 + 6x - 6 - 3$?
?$ = 15x - 18$?
由題意，得方程?$15x - 18 = 12，$?解得?$x = 2$?
?$ (3)$?根據(jù)新運(yùn)算的定義，
?$ m = \frac {9}{2}*(2x) = \frac {9}{2} × (2x)^2 + 2 × \frac {9}{2} × (2x) - 2x$?
?$ = \frac {9}{2} × 4x^2 + 9 × 2x - 2x$?
?$ = 18x^2 + 18x - 2x$?
?$ = 18x^2 + 16x$?
?$ n = (2x - 1)*2 = (2x - 1) × 2^2 + 2 × (2x - 1) × 2 - 2$?
?$ = 4(2x - 1) + 4(2x - 1) - 2$?
?$ = 8x - 4 + 8x - 4 - 2$?
?$ = 16x - 10$?
?$ $?計(jì)算?$m - n$?：
?$ m - n = (18x^2 + 16x) - (16x - 10) = 18x^2 + 10$?
?$ $?因?yàn)?$x$?為有理數(shù)，?$x^2 \geq 0，$?
所以?$18x^2 + 10 ＞ 0，$?
即?$m ＞ n$?
