Question

The line with equation y= 2x + 3 is reflected in the x-axis.

Which of the following is the equation of the new line?

a) y = 2x + 3

b) y = -2x + 3

c) y = 2y + 3

d) y = 1/2 x + 3

e) y = -2x -3

Answer 1

Explanation:

When a graph is reflected about the x-axis, their x-intercept(s) are invariant point(s).

For y = 2x + 3, the x-intercept is -3/2.

Also the slope of the line graph when reflected about the x-axis will change from m to -m.

Therefore the new slope is -2.

We have y = -2x + c.

When x = -3/2, y = 0.

=> (0) = -2(-3/2) + c, c = -3.

Hence the answer is y = -2x - 3. (E)