化简求值:(2x-1)2-(3x+1)(3x-1)+5x(x-1),其中x=?19

化简求值:(2x-1)2-(3x+1)(3x-1)+5x(x-1),其中x=?19.
2025-03-01 03:54:36
推荐回答(1个)
回答1:

原式=4x2-4x+1-9x2+1+5x2-5x
=(4-9+5)x2-(4+5)x+(1+1)
=-9x+2
x=?
1
9
时,原式=-9×(?
1
9
)
+2=3.