Question

tìm x
(x-3)(x^2+3x+9)+x(5-x^2)
anh chị giải dùm!

Answer 1

=x^3+3x^2+9x-3x^2-9X-27+5x-x^5

=-x^5+x^3+5x-27

Answer 2

=x^3+3x^2+9x-3x^2-9x-27+5x-x^5

=-x^5+x^3+5x-27

Answer 3

(x-3)(x^2+3x+9)+x(5-x^2)
<=> (x-3)(x^2+3x+0)+x(5-x^2)=0
<=> x^3+3x^2+9x-3x^2-9x-27+5x-x^3
<=> -27+5x=0
<=> 5x = 27
<=> x= 27/5

Answer 4

\(\Leftrightarrow x^3-27+5x-x^3=0.\)

\(\Leftrightarrow5x=27\)

<=> \(x=\frac{27}{5}\)