Question

I need to rotate the line the given no. of degrees (a) about the x-intercept and (b) about the y-intercept need to write equation of each image. don't know how to start
y = 2x- 3;90degree

Answer 1

For y = -2x - 3, the slope is -2
So the x-intercept, let y=0, is
0 = -2x - 3
x = 3/2

After a rotation of 90º about this point, the slope of the new line is 1/2
and the new equation is
y = (1/2)x + b
but (3/2,0) lies on it
0 = (1/2)(3/2) + b
b = -3/4

so the new line is y = (1/2)x - 3/4

Follow the same method to rotate the original line about the y-intercept.
Let me know what you got
(It is easier, you should be able to write it without even doing any work)

Answer 2

correction:

0 = -2x - 3
x = -3/2

After a rotation of 90º about this point, the slope of the new line is 1/2
and the new equation is
y = (1/2)x + b
but (-3/2,0) lies on it
0 = (1/2)(-3/2) + b
b = 3/4

so the new line is y = (1/2)x + 3/4