please help, involves functions and coordinates

Question

if g is a function such that g(x) = 2x+1, which of the following coordinates satisfies the function?

(A) (-3,-5)

(B) (-6,11)

(C) (5,2)

(D) (13,6)

Answer 1

It is customary to graph functions with the independent variable on the horizontal (x) axis and the dependent variable on vertical (y) axis. here g(x) plays the part of the dependent variable or "y" and x is the independent variable as usual.

Also it is customary to present coordinates as (x,y) pairs, with the independent variable listed first and the dependent variable listed second.

so we have y = g(x) = 2x +1

now just plug in (substitute) the given x value (the first number of the coordinate pair) into the function and see if it yields the correct independent variable given by the second number of the coordinate pair. If you plug it in and it equals the second number, then it satisfies the function, it it doesn't equal the second number it does not satisfy the function.

and we which to know which of the coordinate pairs satisfies the function.

so for (-3,-5) we have y = g(x) = 2(-3) + 1 = -6 + 1 = -5 which does equal -5 so the function is satisfied

for (-6,11) we have y = g(x) = 2(-6) + 1 = -12 + 1 = -11 which does not equal +11 so not satisfied

for (5,2) we have y = g(x) = 2(5) + 1 = 10 + 1 = 11 which does not equal 2 so not satisfied

for (13,6) we have y = g(x) = 2(13) +1 = 26 + 1 = 27 which does not equal 2 so not satisfied

Thus the answer is (A) (-3,-5)