- Thread starter Leah5467
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If f(x) = 2x + 1, then f(-x) = 2(-x) + 1 = -2x +1.

In relation to the title of your post:

f(x) = 2x + 1 does intersect the y-axis at 1.

I'm not exactly sure what your question is

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Find f(-x) for f(x) = 2x + 1.

Please explain why you wrote f(x)=2x and f(x)+1. (I'm guessing that you are not recognizing that f(x) has a specific meaning in this problem, and are just writing "f(x)" to mean "what I've done so far".) It looks like you're trying to solve a different problem than what you showed.

All you have to do for this problem is to replace x in 2x + 1 with (-x).

Now, it is true that 2x + 1 = 2(x + 0.5); but why would you do that in this problem? That is f(x), not f(-x), and it doesn't help toward the answer.Furthermore, the y-intercept of f(x) = 2x + 1

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HallsofIvy, typo? x-intercept is (-1/2, 0)

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f(x) =2x +1 is a straight line with a y-int of 1 and an x-int of -1/2. Correct?

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Draw a quick sketch if you need to.

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The x-intercept of f(x)=2x+1 is found by substituting y=0.

The x-intercept of f(-x) can be found in one of 2 ways:

1. f(-x) = 2(-x)+1 = -2x+1 and substitute y=0 to find x-int is 1/2

OR

2. Recognise that f(-x) is a reflection of f(x) in the y-axis, so the original x-int of -1/2 gets reflectd onto the x-int of 1/2.