If f(x1)+f(x2)=f(x1+x2) for all real numbers x1 and x2, which of the following could define f?
a) f(x)=x+1
b)f(x)=2x
c)f(x)=1/x
d)f(x)=e^x
e)f(x)=x^2

i have no idea how to go about this, if someone can explain it to me.

Moira has a canvas that is 8 inches by 10 inches. she wants to paint a line diagonally from the top left corner to the bottom right corner. approximately how long will the diagonal line be?

Sample response: if the graph passes the horizontaline test, then the function is one to one. functions that are one to one have inverses that a therefore, the inverse is a hinction compare your response to the sample response above. what did you include in your explanation? a reference to the horizontal-line test d a statement that the function is one-to-one the conclusion that the inverse is a function done

Solve the system of equations using the substitution method. {y=−3x+7x=−2y−16 enter your answers in the boxes.