box in there

The answer to the following problem is 17.  However, I don't understand how/why that is.  I would really appreciate anyones time and help in explaining it to me (thank you in advance):

The function f has the property that f(x) = f(x+1) for all numbers x.  If f(4) = 17, what is the value of f(8)?

I've been working on the following problem and know what the answers are (there are 3 options to choose from and all 3 are correct).  I'm struggling to understand how option A is correct, and I'm 99% sure it boils down to not understand a basic number principle.  I would really appreciate someones time and help explaining how option A is correct.

The problem: In the xy-plane, line k is a line that does not pass through the origin.  Which of the following statements individually provide(s) sufficient additional information to conclude that the slop of line k is negative?

Indicate all such statements

A. The x-intercept of line k is twice the y-intercept of line k

B. The product of the x-intercept and the y-intercept of line k is positive

C. Line k passes through the points (alb) and (res), where (a-r)(b-s)<0

All 3 options are correct, but option A is bothering me because if the y intercept is -1, and the x-intercept is +1 then the slope would be positive.  Am I incorrect in assuming that +1 is not twice the value of -1?  I read somewhere that a negative number cannot be twice the value of a positive number (which makes sense), and that a positive number cannot be twice the value of a negative number (which is making my brain hurt).  

I really do appreciate anyones help in explaining this concept to me and help my mind make it over this hurdle.  

Thank you in advance for your time and help.

If 175 is a factor of positive integer x, then x must be a multiple of which of the following integers?

A. 2

B. 3

C. 7

D. 20

E. 350

Could someone please help me with the following question?

If 175 is a factor of positive integer x, then x must be a multiple of which of the following integers?

A. 2

B. 3

C. 7

D. 20

E. 350

I appreciate your time and help. 

Could someone please show me how to solve the following problem?

A grocery store sells bananas for $0.50 each and oranges for $0.80 each.  If a bag of bananas and oranges costs $11.90, and there were a total of 19 bananas and oranges, how many oranges were purchased?

a. 7

b. 8

c. 10

d. 11

e. 12

I appreciate your time and help.  

I'm studying a practice exam for my biology midterm, and one of the questions has the ever-obnoxious "all the above" answers. One of those answers I am struggling with.

The question: Plants may avoid poisoning themselves with the toxic compounds that they use as anti-herbivore defenses by

The answer: evolving a modified target-site for the toxin that is insensitive to the toxin's effect.

What do they mean by target-site? I thought "target-site" meant the system that the toxin is designed to attack??

My professor uses this term frequently, but I can't find a definition for it in our textbook nor online. Could someone please explain what a novel genetic variant is?

I know the CM is clinical modifications, but what makes the ICD-10 CM different from the ICD-10?

Eukaryotes are characterized by:

1. membrane-bound compartments

2. a cytoskeleton

3. active protein localization

4. mitochondria

Could someone please explain what "active protein localization" means?

I am not understanding what a cell-specific-trait is, nor what a non-cell-specific trait is. Please explain.

Which thermodynamic statement below is true?

A. Entropy tends to increase in a closed system

B. Total energy tends to decrease in a closed system

C. Exergonic reactions increase the free energy of a closed system

D. A single living organism can be regarded as a closed system

E. Endergonic reactions are favorable in a closed system

I just got myself confused and could use some clarification. As an electron is passed along the electron transport chain, is ∆G becoming more and more negative, or more and more positive?

CO2 is produced as a waste product when cells perform:

A.) Respiration

B.) Glycolysis

C.) Photosynthesis

D.) The Citric Acid Cycle (TCA, Krebs)

E.) Fermentation

The answer is D, the Citric Acid Cycle. I understand that CO2 is indeed a waste product of the Citric Acid cycle, but why is the answer not also A, Respiration? There are 6CO2 molecules produced per glucose in aerobic respiration. What am I missing?

A good fuel has a high potential energy and high activation energy. I understand why having a high potential energy makes for a good fuel, and I understand the need for an activation energy. But why a high activation energy and not a low activation energy??

Suppose that you drive from St. Paul to Duluth and you average 50 mph. Explain why there must be a time during your trip at which your speed is exactly 50 mph."

Could someone please explain why?

I am reading an article on climate and costal habitat change, and came across this sentence, "Even regains that are forecasted to receive reduced total rainfall are expected to experience higher intensity precipitation events with longer interim periods of drier conditions." Could someone explain what this is saying to me? In particular, what is a precipitation event?

Could someone please explain; In a single slit experiment, should a red or green laser have a wider diffraction pattern?

m = d/a (d = distance between slits and a = slit width) allows us to determine exactly which interference maxima will be missing. Could someone please explain why/how the maxima is missing (in not too difficult of terms)?