They gave you (x,y) = (1,8). The new one is f(-x) so you have to do -1 so -x = -(-1) = +1 = 1."The point (1,8) is on the graph y=f(x). Find the corresponding coordinates of this point on each of the following graphs:
... c) y= -2f(-x)-7."
The textbook answer is (-1,9). I don't understand how they got this answer.
Whichever. It works out the same either way. If you look at "what does the new input need to be, so you get the one they gave you?" then you have to do "-1" becuase they gave you f(x) for x = 1 and then they asked you about f(-x). The only x you had was x = 1 so you had to do something to make "-x" in f(-x) equal the x= 1 they gave you. Or you can plug into your formula. Either way gets you to putting -1 in for your new correspondence point.Thank you, but I'm still a little confused. Why "do I have to do -1 so -x = -(-1) = +1 = 1"? Shouldn't the x correspondence of y = f(x) be (1)/-1 = -1 according to the correspondence equation?