Ejercicio 1 \( f(x)=\sqrt{\left(3 x^{2}-x\right)} \)

V. The number of bacteria in a crop is represented by: \( f(t)=3(4)^{t} \), where \( t \) is measured in hours and \( f(t) \) in thousands. 1. What is the initial number of bacteria? 2. How many are they at 20 minutes? 3. How many are they in half an hour? 4. How many are they after \( 2 \frac{1}{2} \) hours?

\( \sum _ { m - 1 } ^ { 5 } \frac { 7 } { m } = \)

\( \sum _ { m - 1 } ^ { 5 } \frac { 7 } { m } = \)

3) \( f(x)=\left\{\begin{array}{ll}-2^{x}, & x<-4 \\ -|x|, & -4 \leq x \leq 0 \\ 4-x^{2}, & x>0\end{array}\right. \)

If the range of \( y=f(x) \) is \( (-\infty, 1] \), then what is the range of \( y=|f(x)| \) ? The range of \( y=|f(x)| \) is (Type your answer in interval notation.)