解:因為?$(3 - 4x)(2x - 5)=\frac {9}{2},$?
所以?$(3 - 4x)[2(2x - 5)] = 9,$?
所以?$(3 - 4x)(4x - 10)=9。$?
因為?$(3 - 4x)+(4x - 10)=-7,$?
所以?$(3 - 4x)^2 + 4(2x - 5)^2$?
?$=(3 - 4x)^2+[2(2x - 5)]^2$?
?$=(3 - 4x)^2+(4x - 10)^2$?
?$=[(3 - 4x)+(4x - 10)]^2-2(3 - 4x)(4x - 10)$?
?$=(-7)^2-2×9 $?
?$= 49 - 18 $?
?$= 31$?
所以?$(3 - 4x)^2 + 4(2x - 5)^2$?的值為?$31$?