Question

Найти критические точки
f(x)=5+12x-7x³

Answer 1

$f(x)=5+12x-7x^3$
$f'(x)=(5+12x-7x^3)'=12-21x^2$
$f'(x)=0$
$12-21x^2=0$
$21x^2=12$
$7x^2=4$
$x^2= frac{4}{7}$
$x=б sqrt{ frac{4}{7} }$
$x=б frac{2}{ sqrt{7} } }$
$x=б frac{2 sqrt{7} }{7} }$