Question

2) tìm x biết

a) x³-6x²+12x-8=0

b) 8x³-12x²+6x-1=0

c) x³+5x²+2+x+27=0 giải giúp mình cảm ơn nhiều ạ

Answer 1

a) x^3 - 6x^2 + 12x -8 = 0
x^3 - 3.x^2 .2 + 3.x.2^2 - 2^3 = 0
=> ( x-2) = 0
=> x-2=0 <=> x=2

Answer 2

b) 8x^3 - 12x^2 + 6x -1 = 0
(2x)^3 - 3.(2x)^2.1 + 3.2x.1 -1^3 = 0
=> ( 2x - 1 ) = 0
=> 2x-1 = 0 <=> 2x = 1
x = 1/2