Question

tim x biet (2-x)(4-x)-5=0

Answer 1

(2-x)(4-x)-5=0

<=> 8-4x-2x+x²-5=0

<=> x²-6x+3=0

\(\Delta'=9-3=6=>\sqrt{\Delta'}=\sqrt{6}\)

=> \(\hept{\begin{cases}x_1=3-\sqrt{6}\\x_2=3+\sqrt{6}\end{cases}}\)

Answer 2

pt <=> 2.4-4x-2x+x^2-5 = 0

<=> x^2-6x+3 = 0

<=> (x^2-6x+9)-6 = 0

<=> (x+3)^2 = 6

<=> x=.....