7400120138

Question: 
From the following functions, select all that have the second derivative positive on the interval $(0; 1)$.
Project ID: 
7400120138
Answer 1: 
$f(x)=2x^2$
Answer 1 Correct: 
1
Answer 2: 
$f(x)=3x^3$
Answer 2 Correct: 
1
Answer 3: 
$f(x)=\frac{1}{x+1}$
Answer 3 Correct: 
1
Answer 4: 
$f(x)=\frac{1}{x^2}$
Answer 4 Correct: 
1
Answer 5: 
$f(x)=\mathrm{e}^x$
Answer 5 Correct: 
1
Answer 6: 
$f(x)=-\ln\,x$
Answer 6 Correct: 
1
Answer 7: 
$f(x)=\mathrm{tg}\,x$
Answer 7 Correct: 
1
Answer 8: 

$f(x)=\mathrm{cotg}\,x$

Answer 8 Correct: 
1