Question

Giải các phương trình sau:

a) \(x^4-6x^3+11x^2-6x+1=0\)

b) \(6x^4-5x^3-38x^2-5x+6=0\)

c) \(8x^4-34x^3+51x^2-34x+8=0\)

Answer 1

a, \(x^4-6x^3+11x^2-6x+1=0\)

=> \(x^4-6x^3+9x^2+2x^2-6x+1=0\)

=> \(x^2+3x+1=0\)

=> \(\Delta\) =\(b^2-4c\)

=\(3^2.4=5\)

Nên \(\sqrt{\Delta}=5\)

x= \(\dfrac{-b+\sqrt{\Delta}}{2a}=\dfrac{-3+\sqrt{5}}{2}\)

hoặc x= \(\dfrac{b+\sqrt{\Delta}}{2a}=\dfrac{3+\sqrt{5}}{2}\)

Answer 2

Đáp án câu a.

https://giaibaitapvenha.blogspot.com/2017/12/toan-lop-8-ai-so_27.html

Answer 3