Bài làm
a) (12-2x).(8-3x)-6x(x-4)
= 96 - 16x - 36x + 6x² - 6x² + 24x
= 96 - 28x
b,(4x-1)(x+5)-(x-2)(x+3)
= 4x² + 20x - x - 5 - ( x² + 3x - 2x - 6 )
= 4x² + 20x - x - 5 - x² - 3x + 2x + 6
= 3x² - 18x + 1
c,(3x+2)(x-1)-(x+4)(x-1/2)
= 3x² - 3x + 2x - 2 - ( x² - 1/2x + 4x - 2 )
= 3x² - x - 2 - x² - 7/2x + 2
= 2x² - 9/2x
d,(x+1)(1+x-x²+x³-x⁴)-(x-1)(1+x+x²+x³+x⁴)
= x + x² - x³ + x⁴ - x⁵ + 1 + x - x² + x³ - x⁴ - ( x + x² + x³ + x⁴ + x⁵ - 1 - x - x² - x³ - x⁴ )
= 2x - x⁵ + 1 - ( x⁵ - 1 )
= 2x - x⁵ + 1 - x⁵ + 1
= 2x - 2x⁵ + 2