499,842 views
16 votes
16 votes
Which graph is the result of reflecting f(x) = (8)* across the y-axis and then across the x-axis?

--8-7-6-5-4-3
8
7-
6-

th
7
8
co t
7
6
10
5
4-
3
NW
2-
4-
1₁
2

User Artur Vieira
by
2.5k points

1 Answer

10 votes
10 votes

Final answer:

Reflecting the function f(x)=8x first across the y-axis and then across the x-axis results in the line passing through the origin with a positive slope, but it will be below the x-axis, in the third quadrant.

Step-by-step explanation:

To find out which graph is the result of reflecting f(x) = 8x across the y-axis and then across the x-axis, we need to understand how reflections affect the coordinates of points on a graph. Reflecting across the y-axis changes the sign of the x-coordinate of a point, while reflecting across the x-axis changes the sign of the y-coordinate.

For the function f(x) = 8x, initially, the line goes through (0,0) and has a slope of 8, meaning for every 1 unit increase in x, y increases by 8 units. When we reflect this across the y-axis, f(x) becomes f(-x) = 8*(-x) = -8x. This changes the slope to -8, reflecting our line leftwards. Then, reflecting across the x-axis changes our function to -f(-x), which would be -(8*(-x)) = 8x again, however, because of the negative sign applied to the function itself, all y values are inverted, so the slope appears to remain positive, but the line is now below the x-axis, rather than above it.

The new line after both reflections would pass through (0,0) like the original, but each increase of 1 on the horizontal axis will result in a decrease of 8 on the vertical axis because the line is now in the third quadrant.

In conclusion, after reflecting f(x) = 8x across the y-axis and then across the x-axis, the new line will have a positive slope and pass through the origin, but it will lie below the x-axis.