Question

calcule :
a) (x+1).(x+3).(x-1).(x-3)=
b) (x-y).(x²-xy+y²)=
c) (2x+8).(4x+1)=
d) (4x³+5x²y-2xy²).(2x²y+3xy²)=

Answer 1

a)
(x + 1)(x - 1)(x + 3)(x - 3) =

    (x² - 1)    .    (x² - 9) =

        (x⁴ - 9x² - x² + 9) =

x⁴ - 10x² + 9

b)