Question

tìm x:

x³ + x² =36

x³ +5x² -46x =90

Answer 1

\(a,x^3+x^2=36\)

\(\Rightarrow x^6=36\)

\(\Rightarrow x^6=2^6\)

\(\Rightarrow x=2\)

Vậy .......

Answer 2

x=3

Answer 3

x=-9

Answer 4

b: \(x^3+5x^2-46x=90\)

=>\(x^3+5x^2-46x-90=0\)

=>\(x^3+9x^2-4x^2-36x-10x-90=0\)

=>\(\left(x+9\right)\left(x^2-4x-10\right)=0\)

hay \(x\in\left\{-9;2+\sqrt{14};2-\sqrt{14}\right\}\)