Answer:
4) C
5) C
Step-by-step explanation:



Stationary points occur where the derivative is zero. The denominator is positive for all

, so we only need to worry about the numerator.


for all

, so we can divide through:

But

for all

, so this function has no stationary points...
I suspect there may be a typo in the question.
The y intercept is 3
You can also say that the y intercept is at (0,3) which is a more detailed answer. However saying "y intercept is 3" is sufficient enough because the x coordinate of the y intercept is always x = 0.
The y intercept is the location where the graph crosses or touches the y axis. This is at the halfway point between the 2 and 4, so (2+4)/2 = 6/2 = 3
she should add 7 liters of 10% acid solution
Explanation
Step 1
set the equation:
a) let X represents the amount os solution that is 4% acid
let Y represents the amount os solution that is 10% acid
so
I)

if he has 14 liters of 4% acid solution


Step 2
solve the equation :

therefore,
she should add 7 liters of 10% acid solution
I hope this helps you